Task 1: Make conclusions about the population mean based on the test-statistic

value and rejection region when the population variance is assumed to be

unknown.

The Head of the Math Department announced that the mean score of

Grade 9 students in the first periodic examination in Mathematics was

89 and the standard deviation was 12. One student, who believed that

the mean score was less than this, randomly selected 25 students and

computed their mean score. She obtained a mean score of 85. At a

0.01 level of significance, test the student's beliefs.

Answer:

(Show solution if necessary)

Task 2: Make a conclusion about the population mean based on the test-

statistic value and rejection region when the population variance is assumed to be known.

According to a study done last year, the average monthly expenses for mobile phone loads of high school students in Manila were P350.00. A Statistics student believes that this amount has increased since January of this year. Is there a reason to believe that this amount has really increased if a

random sample of 60 students has an average monthly expense for mobile phone loads of P380.00? Use a 0.05 level of

significance. Assume that the population standard deviation is P77.00.

Solution: z = 2.90, CV=1.96, Reject null, The sample mean differ significantly

from the population mean.

Complete Answer: