You must put the percent symbol on percentages. Round decimals to 3 decimal plac
ID: 2901288 • Letter: Y
Question
You must put the percent symbol on percentages.
Round decimals to 3 decimal places before changing decimals to percents.
Ex. 0.3456345 = 0.346 = 34.6%
1. On a particular section of a CPA exam for which the scores were normally distributed with a mean of 600 points and a standard deviation of 70 points.
a) What percent of the students scored lower than 630 on the exam?
b) What percent of the students scored between 630 and 730 on the exam?
c) What percent of the students scored between 600 and 700 on the exam?
d) What percent of the students scored above 700 on the exam?
e) If 900 people take the exam, how many people will score above 700 on the exam?
Explanation / Answer
1. On a particular section of a CPA exam for which the scores were normally distributed with a mean of 600 points and a standard deviation of 70 points.
a) What percent of the students scored lower than 630 on the exam?
P(X<630) = P((X-mean)/s <(630-600)/70)
=P(Z<0.43)
=0.666 (from standard noraml table)
=66.6%
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b) What percent of the students scored between 630 and 730 on the exam?
P(630<X<730) = P((630-600)/70 <Z< (730-600)/70)
=P(0.43 <Z< 1.86)
=0.302
(from standard noraml table)
= 30.2%
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c) What percent of the students scored between 600 and 700 on the exam?
P(600 <X< 700) = P((600-600)/70 <Z< (700-600)/70)
=P(0<Z< 1.43)
=0.424
(from standard noraml table)
= 42.4%
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d) What percent of the students scored above 700 on the exam?
P(X>700) = P(Z> (700-600)/70)
=P(Z>1.43)
=0.076 (from standard noraml table)
= 7.6%
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e) If 900 people take the exam, how many people will score above 700 on the exam?
900* 0.076 =68.4
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