Statistics and Probability Answers

Two-tailed test; variance is known, alpha = 0.05 , n = 40

Number of occurrence of a tossing four coins

What is the computed z of the problem stated below? 

The average monthly salary for a call center representative in the Philippines is P 21,700 with a standard deviation of P 6,000. Find the probability that a group of 64 randomly selected call center representatives has an average salary higher than P 22,000 per month.

The operations manager of a sugar mill in Durban wants to estimate the average size of an order by constructing a 90% confidence interval. An order is measured in the number of pallets shipped. A random sample of 87 orders from customers had an average of 131.6 pallets. Based on information from past records, the operations manager assumes that the number of pallets shipped is normally distributed with a standard deviation of 25 pallets.

What is the confidence interval constructed by the operations manager?

(Round off to the nearest whole numbers.)

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

2. The director of a secretarial school believes that its graduates can type more than75

words per minute. A random sample of 12 graduates has been found to have an

average of 77.2 words per minute with a standard deviation of 7.9 words per minute

in a typing test. Using the 0.05 level of significance, test the claim of the director.

The United States Department of Agriculture reports that, under its standard inspection system one in every 100 slaughtered chickens passes inspection for faecal contamination. Find the probability that, in a random sample of 6 slaughtered chickens, at least one passes inspection for faecal inspection.

1.     The results of a particular examination are shown below in summary form:

Result

Percentage of candidates

Passed with distinction

15

Passed without distinction

42

Failed

43

Total

100

It is known that a candidate gets failed if he obtains less than 40 marks (out of 100), while he must obtain at least 75 marks in order to pass with distinction. Hence determine the mean and standard deviation of the distribution of the marks, assuming it is of normal type.

A quality control want to estimate the proportion of high quality goods out of a batch of products with a 90% confidence level and a margin of error of 5%. How may products must he tes