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# Probability, Mean and Variance Problems

Chapter 4, page 159, exercise 25
A local bank reports that 80 percent of its customers maintain a checking account, 60 percent have a savings account, and 50 percent have both. If a customer is chosen at random, what is the probability the customer has either a checking or a savings account? What is the probability the customer does not have either a checking or a savings account?

Chapter 4, page 165, exercise 36
Dr. Stallter has been teaching basic statistics for many years. She knows that 80 percent of the students will complete the assigned problems. She has also determined that among those who do their assignments, 90 percent will pass the course. Among those students who do not do their homework, 60 percent will pass. Mike Fishbaugh took statistics last semester from Dr. Stallter and received a passing grade. What is the probability that he completed the assignments?

Chapter 3, page 79, exercise 47
The Houston Texas Motel Owner Association conducted a survey regarding weekday motel rates in the area. Listed below is the room rate for business class guests for a sample of 10 motels:
\$ 101 \$ 97 \$ 103 \$ 110 \$ 78 \$ 87 \$ 101 \$ 80 \$ 106 \$ 88

? Compute the sample variance.
? Computer the standard deviation.

#### Solution Summary

The solution gives the complete details of calculation of mean, variance, standard deviation and probability.

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