MATH 105 Lab 05: Normal Distribution Continued

Part 1: Identifying the Mistake

For each normal distribution diagram from the StatCrunch calculator, identify the mistake made. Then fix the mistake and report the correct answer.

Birth weights of babies in the US can be modeled by a normal distribution with mean of 3325 grams and standard deviation of 575 grams.

Compute the probability that a baby weights less than 2500 grams.

Compute how much a baby would need to weigh to be in the 20th percentile.

Compute how much a baby would need to weigh to be in the top 10th percentile.

Part 2: Wristwatch Lifetimes

The mean lifetime of a certain type of wristwatch is 21.6 months, with a standard deviation of 6.3 months. Suppose the lifetimes of these watches follow a normal model.

Part 3: Hoping to Get in to a University

Entry to a certain University is determined by a national test. The scores on this tes are normally distributed with a mean of 500 and a standard deviation of 100. Tom wants to be admitted to this univerisity and he knows that he must score better than at least 70% of the students who took the test.

Part 4: Job Training

The time it takes a randomly selected job applicant to perform a certain task has a distribution that can be approximated by a normal distribution with a mean of 120 seconds and a standard deviation of 20 seconds. The fastest 10% are to be given advanced training.

Part 5: EPA

Environmental Protection Agency (EPA) fuel economy estimates gas efficiency for automobile models. The results of the tested models gave a mean of 24.8 mpg and a standard deviation of 6.2 mpg for highway driving. Assume that the distribution is normal.

Between what two values would the middle 95% of the autos lie with respect to mpg?