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ANEK [815]
4 years ago
6

What is the mean number of hours that high school students spend on homework per week? It is known that the standard deviation o

f the population is 2.2 hours. In a random sample of 40 students, it is found that they average 13 hours per week on homework.
a) What is the standard deviation for this sample?
b) What is the critical value for a 90% confidence interval?
c) What is the critical value for a 95% confidence interval?
Mathematics
1 answer:
viva [34]4 years ago
6 0
This may help you

it is given that the standard deviation  0.8, so we can use  the normal distribution critical value for the 95% confidence interval. 
<span>sample mean = 2.36 </span>
<span>standard deviation = 0.8 </span>
<span>standard error of mean = σ / √ n </span>
<span>standard error of mean = 0.8 / √ 50 </span>
<span>se = 0.8/7.0711 </span>
<span>standard error of mean 0.1131 </span>
<span>Confidence interval 2.36-(0.1131)(1.96) </span>
<span>and 2.36+(0.1131)(1.96) </span>
<span>95% confidence interval :(2.14, 2.58) </span>
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Svetradugi [14.3K]

The probability that the result is green - tail is 1/6.

Spinner has three colors that are  red, green and yellow and coin has two sides that are  head or tail.

<h3>What is the formula for probability?</h3>

Divide the number of events by the number of possible outcomes

The sample space is,{(red - head; red - tail; green - head; green - tail; yellow - head; yellow - tail)}In total there are 6 ways to combine different colors with coin sides.

Therefore ,the probability that the result is green - tail is 1/6.

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brainly.com/question/25870256

5 0
2 years ago
Write an equation in point-slope form for the line that satisfies the given set slope of 4/5, passes through (10,-30
hodyreva [135]

Answer:

y + 30 = 4/5(x - 10)

Step-by-step explanation:

Given the slope, 4/5, and point (10, -30):

We can plug these values into the point-slope form:

y - y1 = m(x - x1)

Let (x1, y1) = (10, -30)

and m = 4/5

y - (-30) = 4/5(x - 10)

y + 30 = 4/5(x - 10)

Therefore, the point-slope form is y + 30 = 4/5(x - 10)  

7 0
3 years ago
PLS HELP!! determine which ordered pair is NOT a solution of y=-4x-2.
Alexxandr [17]
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6 0
3 years ago
The distribution of heights for adult men in a certain population is approximately normal with mean 70 inches and standard devia
KengaRu [80]

Answer:

The interval (meassured in Inches) that represent the middle 80% of the heights is [64.88, 75.12]

Step-by-step explanation:

I beleive those options corresponds to another question, i will ignore them. We want to know an interval in which the probability that a height falls there is 0.8.

In such interval, the probability that a value is higher than the right end of the interval is (1-0.8)/2 = 0.1

If X is the distribuition of heights, then we want z such that P(X > z) = 0.1. We will take W, the standarization of X, wth distribution N(0,1)

W = \frac{X-\mu}{\sigma} = \frac{X-70}{4}

The values of the cumulative distribution function of W, denoted by \phi , can be found in the attached file. Lets call y = \frac{z-70}{4} . We have

0.1 = P(X > z) = P(\frac{X-70}{4} > \frac{z-70}{4}) = P(W > y) = 1-\phi(y)

Thus

\phi(y) = 1-0.1 = 0.9

by looking at the table, we find that y = 1.28, therefore

\frac{z-70}{4} = 1.28\\z = 1.28*4+70 = 75.12

The other end of the interval is the symmetrical of 75.12 respect to 70, hence it is 70- (75.12-70) = 64.88.

The interval (meassured in Inches) that represent the middle 80% of the heights is [64.88, 75.12] .

Download pdf
8 0
3 years ago
Each leg of 45 degree -45 degree -90 degree triangle measure 12 cm what is the length of the hypotenuse
Yuri [45]
A = b = 12 cm


<span>Pythagorean theorem
</span>
a^2+b^2=c^2\\\\ c^2=a^2+a^2\\\\ c^2=2a^2\\\\ c=\sqrt{2a^2}

c=a\sqrt2 formula

c=12\sqrt{2} \ (cm) <-- Answer
3 0
4 years ago
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