Statistics and Probability Answers

The larger the standard deviation of a distribution, the more heterogeneous the scores in that distribution. Is this statement true?explain.

A population consists of the numbers 2, 4, 5, 9, 10. List all possible sample size of 3 from this population without replacement and determine the mean of each sample.

1. The probability that a student must stop at any one traffic light going to NUST from Havana is 0.2. There are 15 traffic lights on the Journey.

a) what is the probability that a student will stop at exactly two of the 15 set of traffic lights?

b) what is the probability that a student will stop at 3 or more of the 15 set of traffic lights?

A teacher realizes that his students' marks on a statistic test are normally distributed with a mean of 62 and a standard deviation of 15. If the teacher wishes to assign minimum marks for grade B is referring to the top 30 per cent of the students' marks in the class, how many marks are required to get a minimum mark for grade B?

Determine the area under the standard normal distribution curve to left of -0.73.

Determine the area under the standard normal distribution curve between -0.91 and 2.5.

Determine the area under the standard normal distribution curve between -0.91 and 2.5.

The Smith Trucking Company claims that the average weight of its delivery

trucks when fully loaded is 6000 pounds with a standard deviation of 120

pounds. 36 trucks are selected at random and their weights recorded.

Within what limits will the average weights of 90% of the 36 trucks lie?

a group of student got the following scores in an achievement test 9,12,15,18,21 and 24. consider samples of size 3 that can be drawn from this population.

The production manager of a large manufacturing company estimates that the mean age of his employees is 22.8 years. The treasurer of the firm needs a more accurate employee mean age figure in order to estimate the cost of an annuity benefit program being considered for employees. The treasurer takes a random sample of 70 workers and finds out that the mean age of the employees sampled is 26.2 years with a standard deviation of 4.6 years. At the 0.01 level of significance, what can the treasurer conclude about the accuracy of the production manager’s estimate?