Final Exam Review Probability Worksheet With Answers (Page 4 of 10) in pdf

28) Suppose a brewery has a filling machine that fills 12 ounce bottles of beer. It is known that the amount of beer

poured by this filling machine follows a normal distribution with a mean of 12.34 ounces and a standard

deviation of 0.04 ounce. Find the probability that the bottle contains between 12.24 and 12.30 ounces.

Answer: .1525

29)

Professor Whata Guy surveyed of his Introduction to Statistics class of 420 students. One of the questions was

"Will you take another mathematics class?" The results showed that 252 of the students said yes. What is the

sample proportion, p?

Answer: 0.6

30) Smith is a weld inspector at a shipyard. He knows from keeping track of good and substandard welds that for

the afternoon shift 5% of all welds done will be substandard. If Smith checks 300 of the 7500 welds completed

that shift, what is the probability that he will find less than 20 substandard welds?

Answer: 0.9066

31) A survey of 500 non-fatal accidents showed that 222 involved the use of a cell phone. Construct a 99%

confidence interval for the proportion of fatal accidents that involved the use of a cell phone.

Answer: (0.387, 0.501)

32) An article a Florida newspaper reported on the topics that teenagers most want to discuss with their parents.

The findings, the results of a poll, showed that 46% would like more discussion about the family's financial

situation, 37% would like to talk about school, and 30% would like to talk about religion. These and other

percentages were based on a national sampling of 513 teenagers. Estimate the proportion of all teenagers who

want more family discussions about school. Use a 90% confidence level.

Answer: .37 ± .035

33) Many people think that a national lobby's successful fight against gun control legislation is reflecting the will of

a minority of Americans. A random sample of 4000 citizens yielded 2250 who are in favor of gun control

legislation. Estimate the true proportion of all Americans who are in favor of gun control legislation using a 90%

confidence interval.

Answer: .5625 ± .0129

34) Construct a 90% confidence interval for the population mean, µ. Assume the population has a normal

distribution. A sample of 15 randomly selected students has a grade point average of 2.86 with a standard

deviation of 0.78.

Answer: (2.51, 3.21)

35) How much money does the average professional football fan spend on food at a single football game? That

question was posed to 10 randomly selected football fans. The sampled results show that sample mean and

standard deviation were $18.00 and $3.30, respectively. Use this information to create a 95% confidence interval

for the mean.

Answer: 18 ± 2.262(3.30/ 10)

36) Construct a 95% confidence interval for the population mean, µ. Assume the population has a normal

distribution. A sample of 25 randomly selected students has a mean test score of 81.5 with a standard deviation

of 10.2.

Answer: (77.29, 85.71)

Final Exam Review Probability Worksheet With Answers Page 4