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Chapter 7: Q. 2.7 (page 438)

The number of unbroken charcoal briquets in a 20-pound bag filled at the factory follows a Normal distribution with a mean of 450 briquets and a standard deviation of 20 briquets. The company expects that a certain number of the bags will be underfilled, so the company will replace for free the 5%of bags that have too few briquets. What is

the minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free?

a. 404

b. 411

c. 418

d. 425

e. 448

Short Answer

Expert verified

c. The minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free is 418

Step by step solution

01

Given Information

Given,

渭=450,蟽=20

USe the Formula :

Z=X-渭蟽

02

Explanation for correct option

Consider,

X~Normal(渭=450,蟽=20)Z~Normal(渭=0,蟽=1)P(Z<-1.645)=0.05;Z=-1.645

The book's Z table can be used to compute the 5th percentile; look for the associated Z value within the table.

Z=X-渭蟽X=蟽*Z+渭X=-1.645*20+450=417.1

Knowing that Z=-1.645

X=418

Therefore, the correct option is (c)

03

Explanation for incorrect option

a. The minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free is not 404

b. The minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free is not 411

d. The minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free is not 425

e. The minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free is not 448.

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Most popular questions from this chapter

Social scientists are interested in the association between high school graduation rate (HSGR, measured as a percent) and the percent of U.S. families living in poverty (POV). Data were collected from all 50 states and the District of Columbia, and a regression analysis was conducted.

The resulting least-squares regression line is given by POV鈭�=59.2-0.620(HSGR) POV^=59.2-0.620(HSGR) with r2=0.802r2=0.802. Based on the information, which of the following is the best interpretation for the slope of the least-squares regression line?

a. For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.896 .

b. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.802.

c. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.620.

d. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.802.

e. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.620.

You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be shown one of the three versions and then asked to reveal her attitude toward the product. You think there may be large differences in the responses of women who are employed and those who are not. Because of these differences, you should use

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More homework Some skeptical Ap庐 Statistics students want to investigate the newspaper's claim in Exercise 11, so they choose an SRS of 100students from the school to interview. In their sample, 45students completed their homework last week. Does this provide convincing evidence that less than 60%of all students at the school completed their assigned homework last week?

a. What is the evidence that less than 60%of all students completed their assigned homework last week?

b. Provide two explanations for the evidence described in part (a).

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