Question

It has been estimated that as many as 70% of the fish caught in certain areas of the Great Lakes have liver cancer due to the pollutants present. Find an approximate 95% range for the percentage of fish with liver cancer present in a sample of 130 fish.

Answer 1

62.12% to 77.88%

Explanation:

We proceed as follows mathematically;

From the question

n=130

Estimate for sample proportion=70% = 70/100 = 0.7 = p

Level of significance is =1-0.95=0.05

Z critical value(using Z table)=1.96

Confidence interval formula is ;

p ± Z * √(p(1-p)/n

= 0.70 ± √(0.7(1-0.7)/130

=(0.6212,0.7788)

Lower confidence interval limit =0.6212

Upper confidence interval limit =0.7788

In percentages , we simply multiply by 100 in both cases =

62.12 % to 77.88%