Question

A study was conducted and it shows that if parents who buy their teenagers a used vehicle and spend between $3,500-10,000. Assuming a 95% confidence interval estimate is desired, calculate the standard deviation and what the sample size should be for a $100 margin of error.

hint: remember the z-score of 0.05 on a standard normal table is 1.96

A.) population standard deviation:

B) sample size for a $100 margin of error (round to the nearest whole number)

Answer 1

a) from thumb rule :

population standard deviation =range/4 =(10000-3500)/4=1625

b)

for 95 % CI value of z=	1.960
standard deviation σ=	1625
margin of error E =	100
required sample size n=(zσ/E)2                                        =	1015.0

( please try 1083.33 for part a and 451 for part b if above comes wrong and revert)