Question

A global insurance company plans to offer life insurance policies in a developing country. It needs to estimate how many years, on average, residents of this country will live by reviewing death records of deceased individuals at a local government office. What (minimum) sample size is needed to form a 97% confidence interval to estimate the true average lifespan of residents in this country to within ±1.5 years? Assume the population standard deviation is known to be 10 years.

Do not round intermediate calculations. Round up your final answer to the next whole number.

Sample size =
death records

Answer 1

Solution

standard deviation =   =10

Margin of error = E = +/ -1.5

At 97% confidence level the z is ,

= 1 - 97% = 1 - 0.97 = 0.03

/ 2 = 0.03 / 2 = 0.015

Z/2 = Z0.015 = 2.17

sample size = n = [Z/2* / E] 2

n = ( 2.17* 10/1.5 )2

n =209.28

Sample size = n =210