Introduction to Statistics

Find the probability using the standard normal distribution.

P(z < 1.49)

• 0.9319

• 0.0681

• 0.6879

• 0.3121

Find the probability using the standard normal distribution.

P(z ≥ –2.31)

• 0.0104

• 0.0087

• 0.9896

• 0.9913

Find the probability using the standard normal distribution.

P(–2.14 < z < 0.95)

• 0.1170

• 0.0681

• 0.1873

• 0.8127

IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the probability a randomly selected person has an IQ score greater than 120.

• 0.9082

• 0.0918

• 0.6293

• 0.3707

IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the probability a randomly selected person has an IQ score between 100 and 120.

• 0.9082

• 0.0918

• 0.4082

• 0.5918

Find the z-score that has 2.68% of the distribution’s area to its right.

• z = 0.9963

• z = –1.93

• z = –0.0037

• z = 1.93

IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What IQ score represents the 98th percentile?

• 131

• 123

• 113

• 145

American children watch an average of 25 hours of television per week with a standard deviation of 8 hours. A random sample of 40 children is selected. What is the probability the mean number of hours of television they watch per week is less than 22?

• 0.3520

• 0.0089

• 0.9911

• 0.6480

Use a correction for continuity to convert the following interval to a normal distribution interval.

The probability of getting at least 80 successes

• x > 80.5

• x > 79.5

• x < 80.5

• x < 79.5