Question

If the mean spending using credit card at Super Store is $110 per week with a population standard deviation of $3 and sample size of 16, the 95% confidence interval will be

Select one:

a. $110 ± 1.46.

b. $110 ± 1.48.

c. $110 ± 1.96.

d. $110 ± 1.44.

Answer 1

= Solution :

Given that,

Point estimate = sample mean = = 110

Population standard deviation =    = 3

Sample size n =16

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96   ( Using z table )

Margin of error = E = Z/2 * ( /n)

= 1.96* ( 3 /  16 )

= 1.48
At 95% confidence interval
is,

± E

$110 ± 1.48.