Statistics and Probability Answers

A researcher knows that the average height of Filipino women is 1.53 m. A random sample of

26 women was taken and found to have a mean height if 1.56 m with a standard deviation of

0.1 m. Is there a reason to believe that the 26 women in the sample are significantly taller than

the others?

Locating Percentiles under the Normal Curve

Solve the following question.

1.) Find the 99th percentiles of a normal curve.

2.) Find the 40th percentiles of a normal curve.

For N= 20 and n = 18, how many possible combinations of samples without replacement can be formed?

Find the 90th. Percentile of the t-distribution if the sample size is 25

Find the 99th. Percentile of the t-distribution with 18 degrees of freedom?

Less than z = -2.33, P(z<2.33)

A printer manufacturing company claims that it's new ink-efficient printer can print an average of 1500 pages of word documents with standard deviation of 60. Thirty-five of these printers showed a mean of 1475 pages. Does this support the company's claim? Use 95% confidence level.

It is claimed that the mean annual salary of call center customer service representative is php 188 584.00. A researcher randomly selected 45 call center customer service representative. He computed the mean of their annual salaries and obtained a mean of php 188 600.00. Does this show that the mean salary of call center customer service representatives is greater than php 188 584.00? Use 0.05 level of significance and assume that the population standard deviation is php 39.50.

A company which produces batteries claims that the life expectancy of their batteries is 90 hours in order to test the claim a consumer interest group tested a random sample of 40 batteries. The test resulted to a mean life expectancy of 87 hours. Using a 0.05 level of significance, can it be concluded that the life expectancy of their batteries is less than 90 hours? Assume that the population standard deviation is known to be 10 hours.

The head of the math department announced that the mean score of grade 11 students in the first periodic examination isn mathematics was 89 and the standard deviation was 12. One student believed that the mean score was less than this, randomly selected 34 students and computed their mean score. She obtained a mean score of 85. At 0.01 level of significance, test the students belief.