A sample of 5 girls showed an average score of 92 on an exam with a standard dev
ID: 3155751 • Letter: A
Question
A sample of 5 girls showed an average score of 92 on an exam with a standard deviation of 2 points. A sample of 3 boys showed an average of 87 with a standard deviation of 1 point. Give the 98% confidence interval for the difference in average scores for boys and girls. a) find the point estimate b) find the standard error of this estimate c) find the margin of error for a 98% confidence interval d) Find a 98% confidence intercal for the difference between the average scores on the exam for boys and girls. Can we conclude the difference between the average scores on the exam for boys and girls is greater than 5 points?
Explanation / Answer
a) Point estimate = 92 - 87 = 5
b) Serror = srqt ( 2^2 / 5 + 1^2 / 3 ) = 1.065
c) alpha / 2 = 0.01 df = 5+3-2 = 6 t=3.143
I: 5 +/- 3.143 * 1.065
5 +/- 3.35
1.65 < miu1- miu2< 8.35
No we cant conclude that because 5 is in the interval