Based on a survey conducted by Greenfield Online, 25-34-year-olds spend the most

Question

Based on a survey conducted by Greenfield Online, 25-34-year-olds spend the most each week on fast food. The average weekly amount of $44 was reported in a May 2009 USA Today Snapshot. Assuming that weekly fast food expenditures are normally distributed with a standard deviation of $14.50, what is the probability that a 25- to 34-year-old will spend a. less than $25 a week on fast food? b. between $30 and $50 a week on fast food? c. more than $75 a week on fast food? Depending on where you live and on the quality of the daycare, costs of daycare can range from $3,000 to $15,000 a year (or $250 to $1, 250 monthly) for one child, according to BabyCenter. Daycare centers in large cities such as New York and San Francisco are notoriously expensive. Suppose that daycare costs are normally distributed with a mean equal to $9,000 and a standard deviation equal to $1, 800. SOURCE: http://www.babycneter.com/a. what percentage of daycare centers will cost between $7, 200 and $10, 800 annually? b. What percentage of daycare centers will cost between $5, 400 and $12, 600 annually? c. What percentage of daycare centers will cost between $3, 600 and $14, 400 annually? d. Compare the results from parts (a) through (c) with the empirical rule. Explain the relationship. As shown in the example on page 126, incomes of junior executives are normally distributed with a standard deviation of $3, 828.

Explanation / Answer

{z} is given by z = (x-mu)/sigma

   mu=900

   sigma=1800

a) P(7200<x<10800) = P((7200-9000)/1800<z<(10800-9000)/1800)

=0.6827

b) P((5400-9000)/1800<z<(12600-9000)/1800)

=0.9545

c)P((3600-9000)/1800<z<(14400-9000)/1800)

=0.9973

from z table

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.