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babymother [125]
2 years ago
10

Construct the indicated confidence interval for the difference between the two population means. Assume that the two samples are

independent simple random samples selected from normally distributed populations. Do not assume that the
population standard deviations are equal.
Q)
A paint manufacturer wished to compare the drying times of two different types of paint. Independent simple random samples of 11 cans of type A and 9 cans of type B were selected and applied to similar surfaces. The drying times, in hours, were recorded. The summary statistics are as follows.

Type A
x1 = 77.5 hrs

s1 = 4.5 hrs

n1 = 11

Type B:
x2 = 63.6 hrs
s2 = 5.1 hrs
n2 = 9

Construct a 98% confidence interval for µ1 - µ2, the difference between the mean drying time for paint of type A and the mean drying time for paint of type B.
Mathematics
1 answer:
MariettaO [177]2 years ago
3 0

Answer:

The 98% confidence interval for the mean is (8.84, 18.96).

Step-by-step explanation:

We have to calculate a 98% confidence interval for the mean.

The sample 1, of size n1=11 has a mean of 77.5 and a standard deviation of 4.5.

The sample 1, of size n1=9 has a mean of 63.6 and a standard deviation of 5.1.

The difference between sample means is Md=.

M_d=M_1-M_2=77.5-63.6=13.9

The estimated standard error of the difference between means is computed using the formula:

s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{4.5^2}{11}+\dfrac{5.1^2}{9}}\\\\\\s_{M_d}=\sqrt{1.841+2.89}=\sqrt{4.731}=2.175

The t-value for a 98% confidence interval is t=2.326.

The margin of error (MOE) can be calculated as:

MOE=t\cdot s_M=2.326 \cdot 2.175=5.06

Then, the lower and upper bounds of the confidence interval are:

LL=M-t \cdot s_M = 13.9-5.06=8.84\\\\UL=M+t \cdot s_M = 13.9+5.06=18.96

The 98% confidence interval for the mean is (8.84, 18.96).

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Political party affiliation is believed to be a very strong indicator of how voters will vote in Presidential Elections. You are
Norma-Jean [14]

Answer:

The best conclusion is that we are 90% that the true population proportion of Republicans that voted for Mitt Romney is between 0.7273 and 0.8106.

Step-by-step explanation:

x% confidence interval:

A confidence interval is built from a sample, has bounds a and b, and has a confidence level of x%. It means that we are x% confident that the population mean is between a and b.

In this question:

The 90% confidence interval for the proportion of Republican voters that had voted for Mitt Romney is (0.7273, 0.8106). The best conclusion is that we are 90% that the true population proportion of Republicans that voted for Mitt Romney is between 0.7273 and 0.8106.

7 0
3 years ago
Please solve these questions. (Geometry)
son4ous [18]
No idea what this is, sorry
5 0
3 years ago
Use the Distributive Property to find 6(14 + 7).<br> F 91<br> G 126<br> H 42<br> J 56
Anni [7]

Answer:

126

Step-by-step explanation:

6(14 + 7).

Distribute

6*14 + 6*7

84 + 42

126

5 0
2 years ago
Read 2 more answers
Help please mathematics 22 -24
Pavel [41]

Answer:  (22) $9,075     (23) $656.25      (24) $217.13

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

Cost Function: C(x) = 5.75x + 8,000

              C(10,000) = 5.75(10,000) + 8,000

                                = 57,500     + 8,000

                                = 65,500

Revenue Function: R(x) = 9.50x

                        R(7,850) = 9.50(7,850)

                                       =    74,575

Profit Function: P(x) = R(x) - C(x)

                                 = 74,575 - 65,500

                                 = 9,075

*****************************************************************************

Retail = Unit Cost + Unit Cost × Markup

         =     $375    +         $375 × .75

         =     $375    +           $281.25

         =     $656.25

*****************************************************************************

$225 but if paid within 10 days there is a 3.5% discount

Discount = $225 - $225 × .035

               =  $225 -     $7.88

               =  $217.13

8 0
3 years ago
Kelly bought two dozen apples she found 1/3 of them were rotten how manu apples were rotten
yKpoI14uk [10]

the answer is 8 apples were rotten

4 0
3 years ago
Read 2 more answers
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