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Mathematics

1 answer:

bazaltina [42]2 years ago

7 0

Answer:

C -8

Step-by-step explanation:

Hope it helps :)!!

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Among a sample of 55 male soldiers the average shower time was found to be 2.95 minutes and the population standard deviation is

Oksanka [162]

Answer: -3.0593

Step-by-step explanation:

The test statistic for the difference between two population mean (when population standard deviations $\sigma_1\ \&\ \sigma_2$ are known ) is given by :-

$z=\dfrac{\overline{x}_1-\overline{x}_2}{\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}}$

where ,

$n_1\ \&\ n_2$ = Sample sizes taken from two populations 1 and 2.

$\overline{x}_1-\overline{x}_2$ = Difference between two Sample mean.

$\sigma_1\ \&\ \sigma_2$ = Standard deviations of populations 1 and 2.

As per given , we have

$n_1=55\ \&\ n_2=58$

$\overline{x}_1=2.95\ \&\ \overline{x}_2=3.3$

$\sigma_1=0.65\ \&\ \sigma_2=0.56$

We assume that the data follows a normal distribution.

Then, the test statistic will be :-

$z=\dfrac{2.95-3.3}{\sqrt{\dfrac{(0.65)^2}{55}+\dfrac{(0.56)^2}{58}}}\\\\=\dfrac{-0.35}{\sqrt{0.0130887}}\\\\=\dfrac{-0.35}{0.1144059}=3.05928278174\approx-3.0593$