Question

A random sample of biostatistics students will be taken to estimate the proportion of students who were also in Calculus II. What sample size would be necessary to propotion to within margin of error 0.10 with 90% confidence? Suppose it is known from the past that such propotion may be between 0.75 and 0.82. What is the size that you need?
a. 46
b. 50
c. 45
d. 51

Answer 1

We have given,                  
Preliminary estimate for proportion (Known) = (0.75+0.82)/2=0.785
Margin of error =E=0.1
Level of significance =1-0.90=0.1
Z critical value is (by using Z table) =1.645
Sample size formula is                   


=45.67      

a. 46