Question

The Old Town Road Group sent its’ top specialists, Kate and Laura (aka Stat Buddees) to get information on why the Sthreet Farmacyst plastic bottles did not explode under pressure. They selected 36 Sthreet Farmacyst bottles and got a mean of 26 with a population standard deviation of 1.5.

a. Find the critical value given a confidence level of 80%.

b. What is the point estimate for the population mean?

c. What would be the standard error of the sample mean?

Answer 1

Solution :

Given that,

(b)Point estimate = sample mean =     = 26

Population standard deviation =    =1.5

Sample size n =36

(a)At 80% confidence level the z is ,

= 1 - 80% = 1 - 0.80 = 0.20

/ 2 = 0.10

Z/2 = Z0.10= 1.28 ( Using z table )

(c)standard error = ( /n)
=   ( 1.5 / 36 )

= 0.25