Question

Calculate the margin of error to estimate the population mean, for the following:

1. 98% confidence level; n =64; sigma square = 144.
2. 99% confidence level; n =120; sigma square = 100.

Answer 1

where,

• z = critical value
• = population standard deviation
• n = sample size

a) 98% confidence level

n =64;

= 144

For 98% confidence interval , the critical factor or z-value is 2.33, i.e. Z =2.33

  

b) 99% confidence level

n =120;

= 100

For 99% confidence interval , the critical factor or z-value is 2.58, i.e. Z =2.58