Question 1

Suppose that, for a certain exam, a teacher grades on a curve according to the figure shown below. It is known that the grades follow a normal distribution with a mean of 40 and a standard deviation of 6. There are 45 students in the class. How many students should receive an A? Please, round your answer to the nearest integer.  __________ student(s)

Accepted Answer

The answer of Suppose that, for a certain exam, a...

Question 2

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 160 pounds and a variance of 16. The material is considered defective if the breaking strength is less than 152 pounds. What is the probability that a randomly selected piece of material will be defective? Please round the answer to the nearest thousandth, if necessary.
A) 0.023
B) 0.159
C) 0.977
D) 0.999
E) 0.001

Accepted Answer

The Z-score for 152 pounds is (152-160)/4 = -2. The probability of a Z-score being less than -2 is approximately 0.023.

Question 3

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 6. What is the variance for this experiment?

Accepted Answer

The answer of Suppose that people's heights (in centimeters) are...

Question 4

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 39.5 inches and a standard deviation of 1.5 inches. About 0.1% of the time, the annual rainfall will be less than how many inches? 
__________ inches

Accepted Answer

The answer of Suppose that the annual rainfall in Ferndale,...

Question 5

Consider two teams in a tug-of-war. Suppose that the breaking strength of a rope (in pounds) is normally distributed, with a mean of 165 pounds and a standard deviation of 4. What is the probability that the rope will break when subjected to a force of 165 or more pounds ? Please round the answer to the nearest thousandth, if necessary.

Accepted Answer

The answer of Consider two teams in a tug-of-war. Suppose...

Question 6

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 170 pounds and a variance of 16. The material is considered defective if the breaking strength is less than 158 pounds. What is the probability that a randomly selected piece of material will be defective? Please round the answer to the nearest thousandth, if necessary.

Accepted Answer

The answer of The breaking strength (in pounds) of a...

Question 7

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 150 pounds and a variance of 4. The material is considered defective if the breaking strength is less than 146 pounds. What is the probability a randomly selected sample will have a breaking strength less than 148 pounds? Please round the answer to the nearest thousandth, if necessary.

Accepted Answer

The answer of The breaking strength (in pounds) of a...

Question 8

The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 160 pounds and a variance of 9. The material is considered defective if the breaking strength is less than 154 pounds. What is the probability a randomly selected sample will have a breaking strength greater than 166 pounds? Please round the answer to the nearest thousandth, if necessary.
A) 0.977
B) 0.023
C) 0.5
D) 0.841
E) 0.159

Accepted Answer

The answer of The breaking strength (in pounds) of a...

Question 9

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. We find the heights of 100 people. How many would you expect to be between 155 and 165 cm tall? Please, round your answer to the nearest integer. 
__________ people

Accepted Answer

The answer of Suppose that people's heights (in centimeters) are...

Question 10

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 39.5 inches and a standard deviation of 3.5 inches. About 2.3% of the time, the annual rainfall will exceed how many inches?
A) 39.5 inches
B) 32.5 inches
C) 43 inches
D) 36 inches
E) 46.5 inches

Accepted Answer

The answer of Suppose that the annual rainfall in Ferndale,...

Question 11

Suppose that, for a certain exam, a teacher grades on a curve according to the graph shown below. It is known that the grades follow a normal distribution with a mean of 40 and a standard deviation of 6. There are 45 students in the class. What score would be necessary to obtain a B?

Accepted Answer

The answer of Suppose that, for a certain exam, a...

Question 12

A package of Toys Galore cereal is marked "Net Wt. 18 oz." The actual weight is normally distributed, with a mean of 18 oz and a variance of 0.01. What percent of the packages will weigh less than 17.9 oz?
A) 15.9%
B) 34.1%
C) 13.6%
D) 50%
E) 2.3%

Accepted Answer

The answer of A package of Toys Galore cereal is...

Question 13

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. What is the probability that a person selected at random is taller than 160 cm? Please, round your answer to three decimal places, if necessary.

Accepted Answer

The answer of Suppose that people's heights (in centimeters) are...

Question 14

A lab test for a new form of e-coli bacteria is not always correct. The hypothesis is that the tested patient has the new e-coli bacteria. Identify a Type I error.
A) The test states that the patient is free of the bacteria, and the patient really does have it.
B) The test states that the patient has the bacteria, and the patient really does not.
C) The test states that the patient has the bacteria, and the patient really does have it.
D) The test states that the patient is free of the bacteria, and the patient is free of it.

Accepted Answer

The answer of A lab test for a new form...

Question 15

A package of Toys Galore cereal is marked "Net Wt. 19 oz." The actual weight is normally distributed, with a mean of 19 oz and a variance of 0.16. 2.3% of the packages will weigh less than how many oz? Please round the answer to the nearest tenth. 
__________ %

Accepted Answer

The answer of A package of Toys Galore cereal is...

Question 16

A package of Toys Galore cereal is marked "Net Wt. 10 oz." The actual weight is normally distributed, with a mean of 10 oz and a variance of 0.01. What percent of the packages will weigh less than 10 oz? Please round the answer to the nearest tenth. 
__________ %

Accepted Answer

The answer of A package of Toys Galore cereal is...

Question 17

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. We find the heights of 100 people. How many would you expect to be taller than 165 cm? Please, round your answer to the nearest integer. 
__________ people

Accepted Answer

The answer of Suppose that people's heights (in centimeters) are...

Question 18

Suppose that the diameter of an electric cable is normally distributed, with a mean of 0.85 inches and a standard deviation of 0.01 inches. Suppose that a sample of the cable is randomly selected. What the probability that the diameter will be greater than 0.84 inches? Please round the answer to the nearest thousandth, if necessary.

Accepted Answer

The answer of Suppose that the diameter of an electric...

Question 19

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 32 inches and a standard deviation of 2 inches. About 2.3% of the time, the annual rainfall will exceed how many inches? 
__________ inches

Accepted Answer

The answer of Suppose that the annual rainfall in Ferndale,...

Question 20

Suppose that the diameter of an electric cable is normally distributed, with a mean of 0.90 inches and a standard deviation of 0.01 inches. Suppose that a sample of the cable is randomly selected. What is the probability that the diameter will exceed 0.91 inches? Please round your answer to the nearest thousandth, if necessary.

Accepted Answer

The answer of Suppose that the diameter of an electric...

Quiz 11: Graphs

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 6. What is the variance for this experiment?

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 39.5 inches and a standard deviation of 1.5 inches. About 0.1% of the time, the annual rainfall will be less than how many inches? __________ inches

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. We find the heights of 100 people. How many would you expect to be between 155 and 165 cm tall? Please, round your answer to the nearest integer. __________ people

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 39.5 inches and a standard deviation of 3.5 inches. About 2.3% of the time, the annual rainfall will exceed how many inches?

Suppose that, for a certain exam, a teacher grades on a curve according to the graph shown below. It is known that the grades follow a normal distribution with a mean of 40 and a standard deviation of 6. There are 45 students in the class. What score would be necessary to obtain a B?

A package of Toys Galore cereal is marked "Net Wt. 18 oz." The actual weight is normally distributed, with a mean of 18 oz and a variance of 0.01. What percent of the packages will weigh less than 17.9 oz?

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. What is the probability that a person selected at random is taller than 160 cm? Please, round your answer to three decimal places, if necessary.

A lab test for a new form of e-coli bacteria is not always correct. The hypothesis is that the tested patient has the new e-coli bacteria. Identify a Type I error.

A package of Toys Galore cereal is marked "Net Wt. 19 oz." The actual weight is normally distributed, with a mean of 19 oz and a variance of 0.16. 2.3% of the packages will weigh less than how many oz? Please round the answer to the nearest tenth. __________ %

A package of Toys Galore cereal is marked "Net Wt. 10 oz." The actual weight is normally distributed, with a mean of 10 oz and a variance of 0.01. What percent of the packages will weigh less than 10 oz? Please round the answer to the nearest tenth. __________ %

Suppose that people's heights (in centimeters) are normally distributed, with a mean of 170 and a standard deviation of 5. We find the heights of 100 people. How many would you expect to be taller than 165 cm? Please, round your answer to the nearest integer. __________ people

Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 32 inches and a standard deviation of 2 inches. About 2.3% of the time, the annual rainfall will exceed how many inches? __________ inches