Chapter 9

Exam 1. 1. All continuous random variables are normally distributed. False. 2. The actual weight of hamburger patties is an example of a continuous random variable. True 3. The college of business administration at acorn University offers a major in finance. Based on historical records, 30% of the college of business students major in Finance. A random sample of 20 students is selected. What is the probability that exactly 3 of the selected students are majoring in Finance? .0716 4. Assume that we have selected a random sample of 25 units from a normally distributed large population. If u = 15, and c2=4, what is the probability that we will obtain a sample mean of less than 14? .0062 5. The normal approximation of the binomial distribution is appropriate when. Np> 5 and n(1-p) >5 6. A newly married couple plans to have four children. Suppose that boys and girls are equal likely each time a child is born. What is the probability the couple will have no more than 2 boys? 62.5% 7. A random variable is said to be discrete if: Its outcome are countable 8. The mean life of pair of shoes is 40 months with a standard deviation of 8 months. If the life of the shoes is normally distributed, how many pairs of shoes out of one million will need replacement before 36 months? 308,500 9. If the sampled population has a mean of 48 and standard deviation 16, then the mean and the standard deviation for the sampling distribution x for n=16 48 and 4 10. The MPG (MILES PER GALLON) for a mid-size car is normally distributed with a mean of 32 and a standard deviation of .8. what is the probability that the MPG for a selected mid-size car would be less that 33.2? 93.32% 11. If the random variable X has a mean of u and a standard deviation g, then (X-u)/g) has a mean and standard deviation respectively. 0 and 1 12. For a binomial probability experiment, with n=150 and p=.2, it is appropriate to use the normal approximation to the binomial distribution. TRUE 13. A computer system uses 4