Question

In: Statistics and Probability

A research firm conducted a survey to determine the mean amount steady smokers spend on cigarettes...

A research firm conducted a survey to determine the mean amount steady smokers spend on cigarettes during a week. They found the distribution of amounts spent per week, followed the normal distribution with the standard deviation of $5. A sample of 49 steady smokers reveal that mean=20.

a). What is the point estimate of the population mean? explain what it indicates

b). using the 95% level of confidence. determine the confidence interval for sample mean. explain what it indicates

Solutions

Expert Solution

Given :-

Standard deviation ( ) = 5,

Sample mean ( ) = 20

Sample size (n) = 49

a)

Therefore the point estimate of the population mean () is equal to sample mean = 20

b)

95% confidence level at alpha=5% then Zc = 1.96

Therefore confidence interval for mean is,

= ( Zc * )

= ( 20 1.96 * ( ) )

= ( 20 1.4 )

=> ( 20 - 1.4) < < ( 20 + 1.4)

18.6 < < 21.4

Therefore, the 95% confident that mean is lies between

( 18.6 , 21.4 ).

orchestra answered 1 year ago
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