Question

You measure 23 watermelons' weights, and find they have a mean weight of 76 ounces. Assume the population standard deviation is 13.5 ounces. Based on this, construct a 99% confidence interval for the true population mean watermelon weight.

Give your answers as decimals, to two places

_____±______ ounces

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 76

Population standard deviation =    =13.5
Sample size = n =23

At 99% confidence level the z is ,

  = 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z_/2 = Z_0.005 = 2.576   ( Using z table )

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

= 2.576* ( 13.5/ 23)

= 7.25

At 99% confidence interval estimate of the population mean is,

+/- E

76+/-7.25