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nikitadnepr [17]

3 years ago

13

Harry collects data from a random sample of seventh-graders. Out of 25 respondents, 10 ride the bus home. Of the 150 seventh-gra

ders who attend Harry’s school, how many would be expected to ride the bus to school?

2 answers:

alekssr [168]3 years ago

7 0

10/25=x/150

x=60

so 60 students

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Ne4ueva [31]3 years ago

3 0

You would divide 150 by 25 which equals 6 and times it by 10 so it would be 60

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SOLVE THIS QUESTION<br>

ASHA 777 [7]

447/250

is the answer to the question

4 0

3 years ago

Read 2 more answers

The mean number of words per minute (WPM) read by sixth graders is 8888 with a standard deviation of 1414 WPM. If 137137 sixth g

Bingel [31]

Noticing that there is a pattern of repetition in the question (the numbers are repeated twice), we are assuming that the mean number of words per minute is 88, the standard deviation is of 14 WPM, as well as the number of sixth graders is 137, and that there is a need to estimate the probability that the sample mean would be greater than 89.87.

Answer:

"The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

Step-by-step explanation:

This is a problem of the <em>distribution of sample means</em>. Roughly speaking, we have the probability distribution of samples obtained from the same population. Each sample mean is an estimation of the population mean, and we know that this distribution behaves <em>normally</em> for samples sizes equal or greater than 30 $\\ n \geq 30$ . Mathematically

$\\ \overline{X} \sim N(\mu, \frac{\sigma}{\sqrt{n}})$ [1]

In words, the latter distribution has a mean that equals the population mean, and a standard deviation that also equals the population standard deviation divided by the square root of the sample size.

Moreover, we know that the variable Z follows a <em>normal standard distribution</em>, i.e., a normal distribution that has a population mean $\\ \mu = 0$ and a population standard deviation $\\ \sigma = 1$ .

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$ [2]

From the question, we know that

The population mean is $\\ \mu = 88$ WPM
The population standard deviation is $\\ \sigma = 14$ WPM

We also know the size of the sample for this case: $\\ n = 137$ sixth graders.

We need to estimate the probability that a sample mean being greater than $\\ \overline{X} = 89.87$ WPM in the <em>distribution of sample means</em>. We can use the formula [2] to find this question.

The probability that the sample mean would be greater than 89.87 WPM

$\\ Z = \frac{\overline{X} - \mu}{\frac{\sigma}{\sqrt{n}}}$

$\\ Z = \frac{89.87 - 88}{\frac{14}{\sqrt{137}}}$

$\\ Z = \frac{1.87}{\frac{14}{\sqrt{137}}}$

$\\ Z = 1.5634 \approx 1.56$

This is a <em>standardized value </em> and it tells us that the sample with mean 89.87 is 1.56<em> standard deviations</em> <em>above</em> the mean of the sampling distribution.

We can consult the probability of P(z<1.56) in any <em>cumulative</em> <em>standard normal table</em> available in Statistics books or on the Internet. Of course, this probability is the same that $\\ P(\overline{X} < 89.87)$ . Then

$\\ P(z$

However, we are looking for P(z>1.56), which is the <em>complement probability</em> of the previous probability. Therefore

$\\ P(z>1.56) = 1 - P(z$

$\\ P(z>1.56) = P(\overline{X}>89.87) = 0.0594$

Thus, "The probability that the sample mean would be greater than 89.87 WPM" is about $\\ P(z>1.56) = 0.0594$ .

5 0

3 years ago

Use Heron's formula to find the area of the triangle. Round to the nearest square foot.

Sphinxa [80]

Answer:

A ≈ 2 ft²

Step-by-step explanation:

The area (A) of a triangle using Heron's formula is

A = $\sqrt{s(s-a)(s-b)(s-c)}$

where s is the semiperimeter and a, b , c the sides of the triangle.

s = $\frac{a+b+c}{2}$ = $\frac{4+4+1}{2}$ = $\frac{9}{2}$ = 4.5

Then

A = $\sqrt{4.5(4.5-4)(4.5-4)(4.5-1)}$

= $\sqrt{4.5(0.5)(0.5)(3.5)}$

= $\sqrt{3.9375}$

≈ 1.9843...

= 2 ft² ( to the nearest square foot )

8 0

2 years ago

The expression is equivalent to the expression

mamaluj [8]

Answer: False

Step-by-step explanation:

For this to be true; x must be squared.

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3 years ago

elect the best answer for the question. 16. Which answer choice contains all the factors of 10? A. 1, 2, 5 B. 2, 5 C. 1, 2, 5, 1

ruslelena [56]

The coorect answer is C. 1, 2, 5, 10

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3 years ago