What average must you exceed to receive a grade better than a C? What averago m

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.6: Summarizing Categorical Data
Problem 42PFA
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2b please

HW
A survey was taken among the freshman at our college to find out how many hours a week
they spent studying for courses for which they were currently enrolled. The data were
normally distributed with a mean of 30 and a standard deviation of 10 hours. What percent of
these freshmen spend:
Examples:
1
a.
b.
C.
d.
More than 40 hours per week studying?
Less than 15 hours per week studying?
More than 25 hours per week studying?
18?√
More than 20 but less than 36 hours per week studying?
√
✓
2) Final averages are typically approximately normally distributed with a mean of 74 and a
standard deviation of 12. Your professor says that the top 10 percent of the class will receive
A, the next 20 percent B, the next 40 percent C, the next 20 percent D, and the bottom 10
percent F.
J
a.
What average must you exceed to obtain an A?
b. What average must you exceed to receive a grade better than a C?
С.
What average must you obtain to pass the course? (You'll need a D or better.)
3) The weights of live turkeys on Mr. Smith's Farm have a standard deviation of 2.8 pounds. Find
the mean weight that his turkeys must attain in order that only 4 percent will weigh less than
20 pounds.
nachir fil
M
4) For a given population of high school seniors, the SAT in mathematics has a mean score of 500
with a standard deviation of 100 (scores are normally distributed). Suppose that a college
honors program will accept only students with a mathematics SAT in the top 20%. What is the
minimum SAT score in mathematics for this honors program?
5) Quick Start Company makes 12-volt car batteries. After many years of product testing, the
company knows that the average life of a Quick Start battery is normally distributed, with a
mean of 45 months and a standard deviation of eight months. If Quick Start guarantees a full
refund on any battery that fails within the 36-month period after purchase, what percentage
of its batteries will the company expect to replace?
u
Transcribed Image Text:HW A survey was taken among the freshman at our college to find out how many hours a week they spent studying for courses for which they were currently enrolled. The data were normally distributed with a mean of 30 and a standard deviation of 10 hours. What percent of these freshmen spend: Examples: 1 a. b. C. d. More than 40 hours per week studying? Less than 15 hours per week studying? More than 25 hours per week studying? 18?√ More than 20 but less than 36 hours per week studying? √ ✓ 2) Final averages are typically approximately normally distributed with a mean of 74 and a standard deviation of 12. Your professor says that the top 10 percent of the class will receive A, the next 20 percent B, the next 40 percent C, the next 20 percent D, and the bottom 10 percent F. J a. What average must you exceed to obtain an A? b. What average must you exceed to receive a grade better than a C? С. What average must you obtain to pass the course? (You'll need a D or better.) 3) The weights of live turkeys on Mr. Smith's Farm have a standard deviation of 2.8 pounds. Find the mean weight that his turkeys must attain in order that only 4 percent will weigh less than 20 pounds. nachir fil M 4) For a given population of high school seniors, the SAT in mathematics has a mean score of 500 with a standard deviation of 100 (scores are normally distributed). Suppose that a college honors program will accept only students with a mathematics SAT in the top 20%. What is the minimum SAT score in mathematics for this honors program? 5) Quick Start Company makes 12-volt car batteries. After many years of product testing, the company knows that the average life of a Quick Start battery is normally distributed, with a mean of 45 months and a standard deviation of eight months. If Quick Start guarantees a full refund on any battery that fails within the 36-month period after purchase, what percentage of its batteries will the company expect to replace? u
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