Question

A Biology teacher wants to see if there is any difference in the abilities of students enrolled in biology today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. Today Five Years Ago 81 85 σ 14.5 8.5 n 81 36 ​ The point estimate for the difference between the means of the two populations is

Answer 1

The point estimate for the difference between the means of the two populations is x1`-x2`= 81-85=-4 where x1` is the mean of the of the first population and x2` is the mean of the second population.

Explanation:

The data given is

Today Five Years Ago

X` 81 85

σ 14.5 8.5

n 81 36

The point estimate for the difference between the means of the two populations is x1`-x2`= 81-85=-4 where x1` is the mean of the of the first population and x2` is the mean of the second population.

The test statistics that will be used is

Z= x1-x2/ √σ₁²/ n₁ + σ₂²/n₂

Z= 81- 85/ √14.5² /81 + 8.5² /36

z= -4/√210.25/81+ 72.25/36

z= -4/2.1454

z= -1.8644