WHat is B i will mark brain thing

A research group needs to determine a 90% confidence interval for the mean repair cost for all car insurance small claims. From

lutik1710 [3]

Answer:

a) $z = 1.645$

b) The should sample at least 293 small claims.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$ , which means that the answer of question a is z = 1.645.

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

(b) If the group wants their estimate to have a maximum error of $12, how many small claims should they sample?

They should sample at least n small claims, in which n is found when

$M = 12, \sigma = 124.88$ . So

$M = z*\frac{\sigma}{\sqrt{n}}$

$12 = 1.645*\frac{124.88}{\sqrt{n}}$

$12\sqrt{n} = 205.43$

$\sqrt{n} = \frac{205.43}{12}$

$\sqrt{n} = 17.12$

$\sqrt{n}^{2} = (17.12)^{2}$

$n = 293$

The should sample at least 293 small claims.

8 0

3 years ago

Find the surface area of a right cone with diameter 30 in. and slant height 8 in.Your answerEXTRA CREDIT: Find the surface area

Anon25 [30]

<u>Answer:</u>

Surface area = 1084 in²

<u>Step-by-step explanation:</u>

To find the surface area of a right cone, we can use the following formula:

$\boxed{{Area = \pi r^2 + \pi rl}}$ ,

where:

• r = radius

• l = slant height.

In the question, we are told that the diameter of the cone is 30 in. Therefore its radius is (30 ÷ 2 = ) 15 in. We are also told that its height is 8 in.

Using this information and the formula above, we can calculate the surface area of the cone:

Surface area = $\pi \times (15)^2 + \pi \times 15 \times 8$

= $345 \pi$

$\approx$ 1084 in²

6 0

2 years ago

the sum of the ages of a man and his wife is at least 104 years if the man is x years old and the wife is x - 4 years old find t

larisa [96]

Answer:

x ≥ 54

Step-by-step explanation:

x+x-4 ≥ 104

2x ≥ 104 + 4

2x ≥ 108

x ≥ 54

6 0

3 years ago

Diving simply the following: 3 power 12÷3 power 7

navik [9.2K]

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${3}^{12} \div {3}^{7} =$

${3}^{12} \times {3}^{ - 7} =$

${3}^{12 - 7} = {3}^{5}$

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

8 0

3 years ago

Read 2 more answers

Abigail made a quilt that has an area of 4800 square inches. The length of the quilt is 1 1/3 times the width of the quilt. What

mafiozo [28]

Answer:

L=132.66

36.18=W

Step-by-step explanation:

length=L

width=W

Area=A

A=L×W

L=11/3W

4800=11/3W×W

4800=11/3W²

3/11·4800=11/3W²·3/11

√1309.1=√W²

36.18=W

L=11/3×36.18

L=132.66

All answers are approximated.

6 0

3 years ago