Unit 8 Check In

Suppose scores on an IQ test are normally distributed with a mean of 95 and a standard deviation of 7. You want to determine the probability that a person who takes the test will score above 102. Which of the following represents the correct calculator work to determine the answer?

• normalcdf (102, 1x10^99, 95, 7)
• normalcdf (1x10^99, 95, 7)
• normalcdf (-1x10^99, 102, 95, 7)
• normalcdf (102, -1x10^99, 95, 7)

Suppose scores on an IQ test are normally distributed with a mean of 95 and a standard deviation of 7. You want to determine what score you would need to earn in order to be in the top 10%. Which of the following expressions represents the correct calculator work to determine this value?

• invNorm (0.10, 95, 7)
• invNorm (0.90, 95, 7)
• normalcdf (0.10, 95, 7)
• normalcdf (0.90, 95, 7)

If the amount of time students work in any given week is normally distributed with a mean of 10 hours per week and a standard deviation of 2 hours, what percent of students work between 8 and 11 hours per week?

• 34.1%
• 38.2%
• 53.2%
• 68.2%

The shape of the normal curve is ___________.

• bell shaped
• flat
• circular
• spiked

The normal distribution is symmetric about the ___________.

• standard deviation
• mean
• variance
• range

Consider the following two normal curves below. Which has the larger mean and which has the larger standard deviation?

• larger mean = a; larger standard deviation = b
• larger mean = a; larger standard deviation = a
• larger mean = b; larger standard deviation = b
• larger mean = b; larger standard deviation = a

Assume the given distributions are normal. A trucking firm determines that its fleet of trucks averages a mean of 12.4 miles per gallon with a standard deviation of 1.2 miles per gallon on cross-country hauls. What is the probability that one of the trucks averages fewer than 10 miles per gallon?

• 0.0082
• 0.0228
• 0.4772
• 0.9772

Assume the given distributions are normal. The mean score on a college placement exam is 500 with a standard deviation of 100. Ninety-five percent of the test takers score below what?

• 336
• 405
• 414
• 664

The Unit 8 Test results for Mrs. Murden and Ms. Devine were normally distributed. The mean and standard deviation for each teacher are shown in the normal curves below. A student in each of their classes scores an 83 on the test. Which student had a more unusual score related to the rest of the class? Explain.

• Mrs. Murden's student because they were closer to the mean.
• Mrs. Murden's student because they were more standard deviations away from the mean.
• Ms. Devine's student because they were closer to the mean.
• Ms. Devine's student because they were more standard deviations away from the mean.

Mrs. Smith's reading class can read an average of 175 words per minute with a standard deviation of 20 words per minute. Which diagram shows the shaded region representing the statement "92% of the class reads at least 150 words per minute"?

• 
• 
• 
•