STAT2210TSAA

Scores on a university exam are Normally distributed, with a mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least C. Using the 68-95-99.7 rule, what percent of students failed to earn a grade of at least C? -16% -32% -5% -2.5%

-16%

A Normal distribution: -can be completely specified by a mean, m, and a standard deviation, s. -can be completely specified by a mean and a standard deviation. -All of the answer options are correct. -has an area of exactly 1 underneath the density curve.

-All of the answer options are correct.

Select all statements that are true for density curves: -The curve satisfies the 68-95-99.7% rule. -The proportion of data values between two numbers 𝑎a and 𝑏b is the area under the curve between 𝑎a and 𝑏b. -The curve is symmetric and single-peaked. -The total area under the curve is 1. -The curve is on or above the horizontal axis

-The proportion of data values between two numbers 𝑎a and 𝑏b is the area under the curve between 𝑎a and 𝑏b. -The total area under the curve is 1. -The curve is on or above the horizontal axis

Birth weights at a local hospital have a Normal distribution, with a mean of 110 oz and a standard deviation of 15 oz. The proportion of infants with birth weights between 125 oz and 140 oz is: 0.819 0.477 0.636 0.136

0.136

Birth weights at a local hospital have a Normal distribution, with a mean of 110 oz and a standard deviation of 15 oz. The proportion of infants with birth weights above 125 oz is: 0.500 0.841 0.159 0.341

0.159

Using the standard Normal distribution tables, the area under the standard Normal curve corresponding to -0.5 < Z < 1.2 is: -0.3085 -0.2815 -0.5764 -0.8849

0.5764

Using the standard Normal distribution tables, what is the area under the standard Normal curve corresponding to Z < 0.75? -0.9599 -0.7500 -0.7734 -0.0401

0.7734

Using the standard Normal distribution tables, the area under the standard Normal curve corresponding to Z > -1.62 is: -0.0526 -0.0044 -0.9956 -0.9474

0.9474

The average time taken for your Internet service provider to remotely resolve a trouble ticket has a Normal distribution, with a mean of 4.3 hours and a standard deviation of 3.1 hour What percentage of the tickets are resolved in less than half an hour? Group of answer choices 85.5% 11.0% 89.1% 14.5%

11.0%

The scores on the Wechsler Adult Intelligence Scale are approximately Normal, with mean 100 and standard deviation is 15. The score needed to be among the highest 10% of all scores is closest to: 125 119 75 81

119

The typical college freshman spends an average of µ = 150 minutes per day, with a standard deviation of σ = 50 minutes, on social media. The distribution of time on social media is known to be Normal. The median of the distribution is: Group of answer choices 180 minutes. 150 minutes. 240 minutes. 75 minutes.

150 minutes

Scores on a university exam are Normally distributed, with a mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least C. Using the 68-95-99.7 rule, what percent of students score below 62? -5% -16% -2.5% -32%

2.5%

The duration (in days) of human pregnancies follows approximately the N(266, 16) distribution. How many days would a human pregnancy need to last to be among the top 10% of all pregnancy duration? Group of answer choices 245.5 days 239.7 days 286.5 days 292.3 days

286.5 days

Scores on the SAT verbal test in recent years follow approximately the N(515, 109) distribution. How high must a student score in order to place in the top 5% of all students taking the SAT? Group of answer choices 336 301 729 694

694

Your friend took an introductory statistics class last year and learned all about density curves. He draws a smooth curve with a long left tail. For such a curve, which of the following is true for the mean and median? Group of answer choices mean > median mean = median There is not enough information to determine any of the answer options. mean < median

mean < median

Your friend took an introductory statistics class last year and learned all about density curves. She tells you that two requirements of a density curve are: Group of answer choices the area above the horizontal axis must be larger than one if there is any area below the axis. the area below the curve and above the horizontal axis must exceed one. the curve is always above the horizontal axis, and the area under the curve is one. the curve is always above the horizontal axis, and the curve is symmetric.

the curve is always above the horizontal axis, and the area under the curve is one.

Suppose you received a score of 95 out of 100 on exam 1. The mean was 79 and the standard deviation was 8. If your score on exam 2 is 90 out of 100, and the mean was 60 with a standard deviation of 15, then you did: Group of answer choices better on exam 1. worse on exam 2. the same on both exams. worse on exam 1.

the same on both exams.