This value is approximate.
====================================================
Explanation:
We have a normal distribution with these parameters
mu = 128 = population meansigma = 30 = population standard deviationThe goal is to find the area under the curve from x = 68 to x = 158, where x is the number of text messages sent per day. So effectively, we want to find P(68 < x < 158).
Let's convert the score x = 68 to its corresponding z score
z = (x-mu)/sigma
z = (68-128)/30
z = -60/30
z = -2
This tells us that the score x = 68 is exactly two standard deviations below the mean mu = 128.
Repeat for x = 158
z = (x-mu)/sigma
z = (158-128)/30
z = 30/30
z = 1
This value is exactly one standard deviation above the mean
-------------------------------------------
The problem of finding P(68 < x < 158) can be rephrased into P(-2 < z < 1)
We do this because we can then use the Empirical rule as shown in the diagram below.
We'll focus on the regions between z = -2 and z = 1. This consists of the blue 13.5% on the left, and the two pink 34% portions. So we will say 13.5% + 34% + 34% = 81.5%
Approximately 81.5% of the the population sends between 68 and 158 text messages per day. This value is approximate because the percentages listed in the Empirical rule below are approximate.
Answer:
C. 81.5%
Step-by-step explanation:
PPPPPLLLLZZZZ HELPPPP
Use the function f(x) = -16x² + 60x + 16 to answer the questions.
Part A: Completely factor f(x). (2 points)
Part B: What are the x-intercepts of the graph of f(x)? Show your work. (2 points
Part C: Describe the end behavior of the graph of f(x). Explain. (2 points)
Part D: What are the steps you would use to graph f(x)? Justify that you can use the answers obtained in Part B and Part C to draw the graph
Here we have the quadratic function:
f(x) = -16*x^2 + 60*x + 16
We can see that it is in standard form:
y = a*x^2 + b*x + c
a) First we want to completely factorize the function f(x).
To do it, we first need to find the roots of f(x).
Remember that for a generic quadratic equation:
a*x^2 + b*x + c = 0
whit roots x₁ and x₂, the factorized form is:
a*(x - x₁)*(x - x₂)
And the roots are given by:
[tex]x = \frac{-b \pm \sqrt{b^2 - 4*a*c} }{2*a}[/tex]
Then for the case of f(x) = -16*x^2 + 60*x + 16, the roots are:
[tex]x = \frac{-60 \pm \sqrt{60^2 - 4*(-16)*16} }{2*(-16)} = \frac{-60 \pm 68}{-32}[/tex]
So the two roots are:
x₁ = (-60 + 68)/-32 = -0.25
x₂ = (-60 - 68)/-32 = 4
Then the factorized form is:
f(x) = -16*(x - 4)*(x + 0.25)
B) We already found the roots, which are:
x₁ = -0.25
x₂ = 4
These are the x-intercepts:
(-0.25, 0) and (4, 0)
C) We can see that the leading coefficient is negative.
This means that the arms of the graph go downwards, so as |x| increases, the value of f(x) tends to negative infinity.
D) To graph f(x) we can find some of the points of the graph (like the x-intercepts and some more of them) and then connect them with a parabola curve, the graph that you will get is the one that you can see below.
If you want to learn more about this topic, you can read:
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The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level.
Step 1 of 2: Suppose a sample of 2845 tenth graders is drawn. Of the students sampled, 2276 read above the eighth grade level. Using the data, estimate the proportion of tenth graders reading at or below the eighth grade level. Enter your answer as a fraction or a decimal number rounded to three decimal places.
Step 2 of 2: Suppose a sample of 2845 tenth graders is drawn. Of the students sampled, 2276 read above the eighth grade level. Using the data, construct the 99% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level. Round your answers to three decimal places.
Answer:
Step 1: The estimate the proportion of tenth graders reading at or below the eighth grade level is 0.2.
Step 2: The 99% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level is (0.181, 0.219).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.
[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]
In which
z is the z-score that has a p-value of [tex]1 - \frac{\alpha}{2}[/tex].
Suppose a sample of 2845 tenth graders is drawn. Of the students sampled, 2276 read above the eighth grade level.
So 2845 - 2276 = 569 read below, and the estimate of the proportion of tenth graders reading at or below the eighth grade level is:
[tex]\pi = \frac{569}{2845} = 0.2[/tex], and the answer to step 1 is 0.2.
The sample size is [tex]n = 2845[/tex]
99% confidence level
So [tex]\alpha = 0.01[/tex], z is the value of Z that has a p-value of [tex]1 - \frac{0.01}{2} = 0.995[/tex], so [tex]Z = 2.575[/tex].
The lower limit of this interval is:
[tex]\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.2 - 2.575\sqrt{\frac{0.2*0.8}{2845}} = 0.181[/tex]
The upper limit of this interval is:
[tex]\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.2 + 2.575\sqrt{\frac{0.2*0.8}{2845}} = 0.219[/tex]
The 99% confidence interval for the population proportion of tenth graders reading at or below the eighth grade level is (0.181, 0.219).
Supervisor: "We are asking everyone to focus on reducing their average transaction
time by 10%. The average transaction time for this location is 6 minutes and 52
seconds."
Employee: "So we have to get the average transaction time down to
5 minutes, 52 seconds
6 minutes, 11 seconds
6 minutes, 18 seconds
6 minutes, 24 seconds
6 minutes, 32 seconds
NEXT >
9514 1404 393
Answer:
6 minutes, 11 seconds
Step-by-step explanation:
In seconds the average transaction time is ...
6 min 52 s = 6(60 s) +52s = 412 s
Reducing this by 10% will cut it to 1 -10% = 90% of this value, or ...
(412 s)(0.9) = 370.8 s
In minutes and seconds, this is 6(60 s) +10.8 s = 6 min 10.8 s.
The average transaction time must be reduced to about 6 min 11 s.
How many minutes will the bus take to complete the trip If a bus completes half a trip at 40 km per hour and the other half at 50 20. if the whole trip was 60 k.m. ?
Answer:
The bus will take 81 minutes to complete the trip.
Step-by-step explanation:
To determine how many minutes will the bus take to complete the trip if a bus completes half a trip at 40 km per hour and the other half at 50 km per hour, and the whole trip was 60 km, the following calculation must be performed:
60/2 = 30
30/40 = 3/4 of an hour = 45 minutes
30/50 = 3/5 of an hour = 36 minutes
45 + 36 = 81
Therefore, the bus will take 81 minutes to complete the trip.
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A warehouse contains ten printing machines, two of which are defective. A company selects seven of the machines at random, thinking all are in working condition. What is the probability that all seven machines are nondefective?
Answer:
0.0667 = 6.67% probability that all seven machines are nondefective.
Step-by-step explanation:
The machines are chosen from the sample without replacement, which means that the hypergeometric distribution is used to solve this question.
Hypergeometric distribution:
The probability of x successes is given by the following formula:
[tex]P(X = x) = h(x,N,n,k) = \frac{C_{k,x}*C_{N-k,n-x}}{C_{N,n}}[/tex]
In which:
x is the number of successes.
N is the size of the population.
n is the size of the sample.
k is the total number of desired outcomes.
Combinations formula:
[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by the following formula.
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
In this question:
10 machines means that [tex]n = 10[/tex]
2 defective, so 10 - 2 = 8 work correctly, which means that [tex]k = 8[/tex]
Seven are selected, which means that [tex]n = 7[/tex]
What is the probability that all seven machines are nondefective?
This is P(X = 7). So
[tex]P(X = x) = h(x,N,n,k) = \frac{C_{k,x}*C_{N-k,n-x}}{C_{N,n}}[/tex]
[tex]P(X = 7) = h(7,10,7,8) = \frac{C_{8,7}*C_{2,0}}{C_{10,7}} = 0.0667[/tex]
0.0667 = 6.67% probability that all seven machines are nondefective.
Convert 2546 in base 10 to base 5
Answer:
40141
Step-by-step explanation:
Use the function f(x) to answer the questions:
f(x) = 2x2 − x − 10
Part A: What are the x-intercepts of the graph of f(x)? Show your work.
Answer:
x=(-2,0) and x=(5/2,0)
Step-by-step explanation:
To find x-intercepts you set f(x), or y, to 0 and then solve.
[tex]0=2x^2-x-10\\Factor!\\0=(x+2)(2x-5)\\x+2=0\\x=2\\2x-5=0\\2x=5\\x=\frac{5}{2}[/tex]
The x-intercepts of the graph of f(x) is (-2, 0) and (5/2, 0).
The function is given as:
[tex]f(x) = 2x^2 - x - 10[/tex]
We need to find the points at which the given function crosses the x-axis.
What is the x-intercept of a function?It is the point at which the given function crosses the x-axis.
The x-intercept is found by setting y = 0 or f(x) = 0.
Given function,
[tex]f(x) = 2x^2 - x - 10[/tex]
Let's set f(x) = 0.
[tex]2x^2 - x - 10 = 0[/tex]
Solve the equation for x.
[tex]2x^2 - x - 10\\2x^2 - (5 - 4)x - 10\\2x^2 - 5x + 4x - 10\\x(2x-5) +2(2x - 5)\\(x+2)(2x-5)[/tex]
Now we have,
x+2 = 0 and 2x - 5 = 0
x = -2 and x = 5 / 2
We already know that y = 0 so the points at which the function intercepts with the x-axis are:
(-2, 0) and (5/2, 0).
The x-intercepts of the graph of f(x) is (-2, 0) and (5/2, 0).
Learn more about x-intercepts of a function here:
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Suppose that, in the past, 40% of all adults favored capital punishment. Do we have reason to believe that the proportion of adults favoring capital punishment today has increased if, in a random sample of 15 adults, 8 favor capital punishment? Use a 0.05 level of significance.
Answer:
The p-value of the test is 0.1469 > 0.05, which means that there is no reason to believe that the proportion of adults favoring capital punishment today has increased, using a 0.05 level of significance.
Step-by-step explanation:
Suppose that, in the past, 40% of all adults favored capital punishment. Test if the proportion has increased:
At the null hypothesis, we test if the proportion is still of 40%, that is:
[tex]H_0: p = 0.4[/tex]
At the alternative hypothesis, we test if the proportion has increased, that is, is greater than 40%, so:
[tex]H_1: p > 0.4[/tex]
The test statistic is:
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
In which X is the sample mean, [tex]\mu[/tex] is the value tested at the null hypothesis, [tex]\sigma[/tex] is the standard deviation and n is the size of the sample.
0.4 is tested at the null hypothesis:
This means that [tex]\mu = 0.4, \sigma = \sqrt{0.4*0.6}[/tex]
Random sample of 15 adults, 8 favor capital punishment.
This means that [tex]n = 15, X = \frac{8}{15} = 0.5333[/tex]
Value of the test statistic:
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
[tex]z = \frac{0.5333 - 0.4}{\frac{\sqrt{0.4*0.6}}{\sqrt{15}}}[/tex]
[tex]z = 1.05[/tex]
P-value of the test and decision:
The p-value of the test is the probability of finding a sample proportion of 0.5333 or more, which is 1 subtracted by the p-value of z = 1.05.
Looking at the z-table, z = 1.05 has a p-value of 0.8531.
1 - 0.8531 = 0.1469.
The p-value of the test is 0.1469 > 0.05, which means that there is no reason to believe that the proportion of adults favoring capital punishment today has increased, using a 0.05 level of significance.
There are two machines available for cutting corks intended for use in wine bottles. The first produces corks with diameters that are normally distributed with mean 3 cm and standard deviation 0.10 cm. The second machine produces corks with diameters that have a normal distribution with mean 3.04 cm and standard deviation 0.04 cm. Acceptable corks have diameters between 2.9 cm and 3.1 cm. What is the probability that the first machine produces an acceptable cork
Answer:
0.6827
Step-by-step explanation:
Given that :
Mean, μ = 3
Standard deviation, σ = 0.1
To produce an acceptable cork. :
P(2.9 < X < 3.1)
Recall :
Z = (x - μ) / σ
P(2.9 < X < 3.1) = P[((2.9 - 3) / 0.1) < Z < ((3.1 - 3) / 0.1)]
P(2.9 < X < 3.1) = P(-1 < Z < 1)
Using a normal distribution calculator, we obtain the probability to the right of the distribution :
P(2.9 < X < 3.1) = P(1 < Z < - 1) = 0.8413 - 0.1587 = 0.6827
Hence, the probability that the first machine produces an acceptable cork is 0.6827
Find the largest factor of 2520 that is not divisible by 6.
Suppose you obtain a chi-square statistic of 67.81. Are your results statistically significant if the critical value obtained from the distribution of chi-square is 3.84 with an alpha level of .05? Explain.
Answer:
Result is statistically significant.
Step-by-step explanation:
Given that :
Chisquare statistic, χ² = 67.81
Critical value for the distribution, χ²critical = 3.84
α = 0.05
The Decison region :
If χ² statistic > Critical value ; Reject H0 ; this. Eans that result is statistically significant.
Therefore, since, 67.81 > 3.84 ; This means that the result is statistically significant at 0.05
what is the answer to EVAULATE 8+-9+-6
Answer:
11
Step-by-step explanation:
8 + 9 + -6
8 + 9 = 17
17 + (-6) = 11
Answered by Gauthmath
Find how much money needs to be deposited now into an account to obtain $7,300 (Future Value) in 6
years if the interest rate is 2.5% per year compounded monthly (12 times per year).
The final amount is $
Round your answer to 2 decimal places
Answer:
x= $6,284.15
Step-by-step explanation:
7300 = x(1 + .025/12)^72
x = [tex]\frac{7300}{(1 + \frac{.025}{12} )^{72} }[/tex]
x= $6,284.15
Show that the equation 2x + 3 cos x + e ^ x = 0 has a root on the interval [- 1, 0]
If x = -1, you have
2(-1) + 3 cos(-1) + e ⁻¹ ≈ -0.0112136 < 0
and if x = 0, you have
2(0) + 3 cos(0) + e ⁰ = 4 > 0
The function f(x) = 2x + 3 cos(x) + eˣ is continuous over the real numbers, so the intermediate value theorem applies, and it says that there is some -1 < c < 0 such that f(c) = 0.
A dairy needs 230 gallons of milk containing 6% butterfat. How many gallons each of milk containing 8% butterfat and milk containing 3% butterfat must be used to obtain the desired 230 gallons?
Answer:
138 gallons - milk containing 8% butterfat , 92 gallons - milk containing 3% butterfat
Step-by-step explanation:
Firstly, find the quantity of butterfat in the dairy needs of milk
230/100*6= 2.3*6=13.8 gallons of butterflat
1) Consider gallons each of milk containing 8% butterfat and milk containing 3%, suppose we need x gallons of milk containing 8 percents butterfat, then we need 230-x gallons of milk containing 3percent butterfat.
Then the quantity of the butterfat in the 8percents fat milk is x/100*8= 0.08x
the quantity of the butterfat in the 3percents fat milk is (230-x)/100*3=
=0.03 (230-x) = 6.9-0.03x The amount of butterfat of the both milk containing 8% butterfat and milk containing 3%is equal to 13.8 gallons
Then 0.08x+6.9-0.03x=13.8
0.05x=6.9
x=6.9/0.05= 138 -milk 8 percents
230-x= 230-138= 92
The prices of paperbacks sold at a used bookstore are approximately Normally distributed, with a mean of $7.85 and a standard deviation of $1.25.
Use the z-table to answer the question.
If the probability that Joel randomly selects a book in the D dollars or less range is 56%, what is the value of D?
$4.46
$7.75
$8.04
$8.10
(C) 8.04
Answer:
The answer you want is indeed, (C).
8.04
ED2021
Answer:
C) 8.04
Step-by-step explanation:
edge 2023
Your car can go 2/7 of the way on 3/8 of a tank of gas how far can you go on the remaining gas?
A proportion that can be used is a/b=c/d
Answer:
10/21 of the distance
Step-by-step explanation:
2/7 distance
------------------
3/8 tank
The rest of the tank is 8/8 - 3/8 = 5/8
2/7 distance x
------------------ = ----------------------
3/8 tank 5/8 tank
Using cross products
2/7 * 5/8 = 3/8x
10/56 = 3/8x
Multiply each side by 8/3
10/56 * 8/3 = 3/8x * 8/3
10/3 * 8/56=x
10/3 * 1/7 =x
10/21 =x
10/21 of the distance
Tay-Sachs disease is a genetic disorder that is usually fatal in young children. If both parents are carriers of the disease, the probability that their offspring will develop the disease is approximately 0.25. Suppose that a husband and wife are both carriers and that they have four children. If the outcomes of the four pregnancies are mutually independent, what are the probabilities of the following events?
a. All three children will develop Tay–Sachs disease.
b. Only one child will develop Tay–Sachs disease.
c. The third child will develop Tay–Sachs disease, given that the first two did not.
Lo siento mucho, necesito los puntos porque estoy en una prueba.
Find the value of X. Round to the
nearest tenth.
Answer: 8.1
Step-by-step explanation:
4^2 + X^2 = 9^2
16 + X^2 = 81
X^2 = 81-16
X = sqrt 65 = 8.1
give an example of a piecewise function
Answer:
f(x) = 6 when -5 < x ≤ -1
Step-by-step explanation:
Solve this pleaseeeeeeeeeee
Answer:
10d
Step-by-step explanation:
5d on 1 side, double it to get 10d cuz from Point O to Point D, y increases from 0 to 5d and since the triangles are congruent, we can add another 5d (or in total 10d).
Which expression is equivalent to (3 squared) Superscript negative 2?
Answer:
–81
Step-by-step explanation:
Assume that the matrices below are partitioned conformably for block multiplication. Compute the product.
[I 0] [W X]
[K I] [Y Z]
Multiplying block matrices works just like multiplication between regular matrices, provided that component matrices have the right sizes.
[tex]\begin{bmatrix}\mathbf I&\mathbf 0\\\mathbf K&\mathbf I\end{bmatrix}\begin{bmatrix}\mathbf W&\mathbf X\\\mathbf Y&\mathbf Z\end{bmatrix} = \begin{bmatrix}\mathbf{IW}+\mathbf{0Y}&\mathbf{IX}+\mathbf{0Z}\\\mathbf{KW}+\mathbf{IY}&\mathbf{KX}+\mathbf{IZ}\end{bmatrix}[/tex]
[tex]\begin{bmatrix}\mathbf I&\mathbf 0\\\mathbf K&\mathbf I\end{bmatrix}\begin{bmatrix}\mathbf W&\mathbf X\\\mathbf Y&\mathbf Z\end{bmatrix} = \begin{bmatrix}\mathbf W+\mathbf 0&\mathbf X+\mathbf 0\\\mathbf{KW}+\mathbf Y&\mathbf{KX}+\mathbf Z\end{bmatrix}[/tex]
[tex]\begin{bmatrix}\mathbf I&\mathbf 0\\\mathbf K&\mathbf I\end{bmatrix}\begin{bmatrix}\mathbf W&\mathbf X\\\mathbf Y&\mathbf Z\end{bmatrix} = \begin{bmatrix}\mathbf W&\mathbf X\\\mathbf{KW}+\mathbf Y&\mathbf{KX}+\mathbf Z\end{bmatrix}[/tex]
(I assume I is the identity matrix and 0 is the zero matrix.)
Find the dimensions of a rectangle with perimeter 108 m whose area is as large as possible. (If both values are the same number, enter it into both blanks.) m (smaller value) m (larger value)
Answer:
27 by 27
Step-by-step explanation:
Let the sides be x and y. The problem is essentially asking:
Given 2(x+y)=108, maximize xy.
We know that x+y=54. By the Arithmetic Mean - Geometric Mean inequality, we can see that [tex]\frac{x+y}{2} \ge \sqrt{xy[/tex]. Substituting in x+y=54, we get [tex]27\ge\sqrt{xy}[/tex], meaning that [tex]729 \ge xy[/tex]. Equality will only be obtained when x=y (in this case it will generate the maximum for xy), so setting x = y, we can see that x = y = 27. Hence, 27 is the answer you are looking for.
The diameter of a circle has endpoints P(-12, -4) and Q(6, 12).
Write an equation for the circle. Be sure to show and explain all work.
9514 1404 393
Answer:
(x +3)² +(y -4)² = 145
Step-by-step explanation:
The center of the circle is the midpoint of the given segment PQ. If we call that point A, then ...
A = (P +Q)/2
A = ((-12, -4) +(6, 12))/2 = (-12+6, -4+12)/2 = (-6, 8)/2
A = (-3, 4)
The equation of the circle for some radius r is ...
(x -(-3))² +(y -4)² = r² . . . . . . where (-3, 4) is the center of the circle
The value of r² can be found by substituting either of the points on the circle. If we use Q, then we have ...
(6 +3)² +(12 -4)² = r² = 9² +8²
r² = 81 +64 = 145
Then the equation of the circle is ...
(x +3)² +(y -4)² = 145
find the equation of Straight line which passes through the point A(-5,10) makes equal intercept on both axes.
Answer:
y = -x + 5
Step-by-step explanation:
The point is in quadrant 2, so the line must pass through points that look like (a, 0) and (0, a) where a is a positive number. The slope of such a line is -1.
If (x, y) is a point on the line, then the slope between points (x, y) and (-5, 10) is 1, and you can write
[tex]\frac{y-10}{x-(-5)}=-1\\y-10 = -1(x+5)\\y-10=-x-5\\y=-x+5[/tex]
Find the measure of one interior angle of a regular 7-gon
Answer:
128.57 degrees
Step-by-step explanation:
To find the measure of an interior angle of a regular polygon with [tex]n[/tex] sides, we can use the formula: [tex]\frac{180(n-2)}{n}[/tex]
To find the measure of an interior angle of a polygon with 7 sides, all we have to do is plug in 7 into the formula:
[tex]\frac{180(7-2)}{7}[/tex]
7 minus 2 equals 5, so the answer is
[tex]180(5)[/tex]÷[tex]7[/tex]
180 times 5 is equal to 900, and 900 divided by 7 is approximately 128.57
Find the length of the arc.
A. 21/π4 in
B. 18π in
C. 45/π8 in
D. 1890π in
Answer:
we know that all Lenght of circle is 2πr so 2*π*7=14π
Step-by-step explanation:
14π equal to 360°
but we need just 135° so we should write it kind of radian(π)
if 14π=360°
x=135°
14π*135=360°*x 14π*27=72*x ........= 14π*3=8*x
7π*3=4*x ....... X=21π/4
The length of the arc is 21/π4 in
An answer is an option A. 21/π4 in
What is the arc of the circle?The arc period of a circle can be calculated with the radius and relevant perspective using the arc period method.
⇒angle= arc/radius
⇒ 135°=arc/7
⇒ arc =135°*7
⇒arc=135°*π/180° *7in
⇒arc = 21/π4 in
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Two chords in a circle intersect. One chord is made of 6 and 5, and the other is made of x +1 and x. What is x?
Answer:
x = 5 and -6
Step-by-step explanation:
Using the intersecting chord theorem which states that the products of the lengths of the line segments on each chord are equal.
Hence:
let
a = 6, b = 5, c = x+1 and d = x
Therefore, ab = cd
6*5 = x(x+1)
30 = x²+x
x²+x - 30 = 0
x²+ 6x - 5x - 30 = 0
x(x+6) - 5(x+6) =0
(x-5)(x+6) = 0
x-5 =0 and x+6 = 0
x = 5 and -6