# MCQs-Probability, Mean, Variance & S.D.

1) In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the mean and variance of X. Place the mean in the first blank_______________ and place the variance in the second blank____________________________

2) A die is rolled 360 times. Find the standard deviation for the number of 3 s that will be rolled.

A. 60

B. 50

C. 7.1

D. 5.9

3) A certain system has 2 components. There are 10 different models of the first component and 10 different of the second. Any first component can be paired with any second component. A salesman must select 2 of the first component and 3 of the second to take on a sales call. How many different systems can the salesman select? Place your answer in the blank. Do not use commas_________________

4) If 1.5% of the bolts made by an automotive factory are defective, what is the probability that in a shipment of 200 bolts, there are 6 defective bolts? Place your answer, rounded to four decimal places, in the blank_______________________

5) If a student randomly guesses at 20 multiple choice questions, find the probability that the student gets exactly four correct. Each question has 4 possible choices.

A. 0.19

B. 0.17

C. 0.08

D. 0.23

6) A pet supplier has a stock of parakeets of which 10% are blue parakeets. A pet store orders 3 parakeets from this supplier. If the supplier selects the parakeets at random, what is the chance that the pet store gets exactly one blue parakeet.

A. 0.081

B. 0.243

C. 0.027

D. 0.003

#### Solution Summary

The solution provides step by step method for the calculation of probability, mean, variance and standard deviation for a couple of multiple choice questions. Formula for the calculation and Interpretations of the results are also included.