How large of a sample would be required in order to estimate

How large of a sample would be required in order to estimate the mean number at a 80% confirdence level with an error at most 0.11?

Mean: 7.9

Variance: 1.44

Solution

How large of a sample would be required in order to estimate the mean number at a 80% confirdence level with an error at most 0.11?

Mean: 7.9

Variance: 1.44

For 80%, z=1.282

d=0.11

s² =1.44

Sample size = (z²*s²)/d²

= (1.282² *1.44)/0.11²

=195.59

The sample size required= 196