Question

we want to make a 95% confidence interval for the true jumping distance of all kangaroos. we think that the standard deviation of jumping distance is roughly 4ft. we would like the margin of error to be 1ft. how many kangaroos do we need?

a) 62

b) 52

c) 72

Answer 1

Option a) is correct.

62

We have given here,              
              
Population standard deviation =4 ft
Margin of error =E=1 ft
Level of significance =   1-0.95=0.05
Z critical value is (by using Z table)=1.96
Sample size formula is               


=61.46              
Therefore, sample size approximately will be 62