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A certain class of 90 students took a typing proficiency tes
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20 Nov 2019, 04:20
20 Nov 2019, 04:20
Expert Reply
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Question Stats:
69% (02:09) correct
30% (01:58) wrong based on 13 sessions
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A certain class of 90 students took a typing proficiency test. The average (arithmetic mean) score of the students who passed the test was 84, and the average score of the students who failed the test was 60. If the average score of all students was 80, how many students passed the test?
A. 15
B. 20
C. 42
D. 70
E. 75
Kudos for the right answer and solution.
A. 15
B. 20
C. 42
D. 70
E. 75
Kudos for the right answer and solution.
Re: A certain class of 90 students took a typing proficiency tes
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20 Nov 2019, 13:14
20 Nov 2019, 13:14
3
Set up two simultaneous equation
x the number of students who pass the test
Y the number of students who fail
X + Y = 90
84X + 60Y = (80*90)
Y = 90 - X
84X + 60(90 - X) = 7200
24X = 1800
X = 75
The solution is E
x the number of students who pass the test
Y the number of students who fail
X + Y = 90
84X + 60Y = (80*90)
Y = 90 - X
84X + 60(90 - X) = 7200
24X = 1800
X = 75
The solution is E
Re: A certain class of 90 students took a typing proficiency tes
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20 Nov 2019, 23:21
20 Nov 2019, 23:21
Great explanatation
