A random sample of 5 months in an urban area showed an average of 28 mail...

A random sample of 5 months in an urban area showed an average of 28 mail carriers were bitten by dogs. If the population is normal and the standard deviation of the sample is 3 find the 95% confidence interval for the population mean.

Solutions

Expert Solution

Solution :

Given that,

= 28

s =3

n =5

Degrees of freedom = df = n - 1 = 5- 1 = 4

a ) At 95% confidence level the t is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2= 0.05 / 2 = 0.025

t /2,df = t0.025,4 =2.776 ( using student t table)

Margin of error = E = t/2,df * (s / $\sqrt$ n)

=2.776 * (3 / $\sqrt$ 5)

= 3.7

The 95% confidence interval mean is,

- E < < + E

28 - 3.7 < < 28+3.7

24.3 < < 31.7

orchestra answered 1 year ago

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