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Updated on: 01 Oct 2019, 20:56
Originally posted by EMPOWERgmatRichC on 28 Sep 2019, 15:50.
Last edited by EMPOWERgmatRichC on 01 Oct 2019, 20:56, edited 1 time in total.
Last edited by EMPOWERgmatRichC on 01 Oct 2019, 20:56, edited 1 time in total.
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EMPOWERgmat PS Series:
Block 1, Question 4
A College runs 25 classes on Monday. Ten of the classes have an average size of 14.2 students while the other fifteen classes have an average size of 12.2 students. What is the average class size, in students, of all 25 classes run on Monday?
A. 12.5
B. 13
C. 13.2
D. 13.5
E. 14
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To be eligible, your explanation must be submitted within the 48 hour window after this post was created and should explain your reasoning why the answer you chose is correct
The OA and official explanation will be held until the 48 hour window has lapsed.
Block 1, Question 4
A College runs 25 classes on Monday. Ten of the classes have an average size of 14.2 students while the other fifteen classes have an average size of 12.2 students. What is the average class size, in students, of all 25 classes run on Monday?
A. 12.5
B. 13
C. 13.2
D. 13.5
E. 14
48 Hour Window To Win An $85 EMPOWERgmat Tuition Credit (1 Month Free!)
Share your explanation! The GMAT Club member with the most verified Kudos in total on the 5 question PS Block 1 question pack will win an $85 EMPOWERgmat tuition credit, which will entitle the winner to a full month of complete access to the EMPOWERgmat system. Even if you're not sure about your answer or your rationale, share your explanation to help boost your learning and earn a chance to win.
To be eligible, your explanation must be submitted within the 48 hour window after this post was created and should explain your reasoning why the answer you chose is correct
The OA and official explanation will be held until the 48 hour window has lapsed.
28 Sep 2019, 17:17
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Given information
Total number of classes on Monday = 25
The average size of 10 classes = 14.2 students
The average size of the other 15 classes = 12.2 students
Therefore, the average class size, in students, of all 25 classes run on Monday = \(\frac{10x14.2 + 15x12.2}{25}\) = \(\frac{142 + 183}{25}\) = 13
Hence, the correct answer is option B. 13
Note:
The weighted average is an average in which each quantity to be averaged is assigned a weight. These weightings determine the relative importance of each quantity on average. Weightings are the equivalent of having that many like items with the same value involved in the average.
Formula
Weighted Average= \(\frac{Sum of weighted terms}{Total number of terms}\)
Total number of classes on Monday = 25
The average size of 10 classes = 14.2 students
The average size of the other 15 classes = 12.2 students
Therefore, the average class size, in students, of all 25 classes run on Monday = \(\frac{10x14.2 + 15x12.2}{25}\) = \(\frac{142 + 183}{25}\) = 13
Hence, the correct answer is option B. 13
Note:
The weighted average is an average in which each quantity to be averaged is assigned a weight. These weightings determine the relative importance of each quantity on average. Weightings are the equivalent of having that many like items with the same value involved in the average.
Formula
Weighted Average= \(\frac{Sum of weighted terms}{Total number of terms}\)
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29 Sep 2019, 01:36
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EMPOWERgmatRichC
EMPOWERgmat PS Series:
Block 1, Question 4
A College runs 25 classes on Monday. Ten of the classes have an average size of 14.2 students while the other fifteen classes have an average size of 12.2 students. What is the average class size, in students, of all 25 classes run on Monday?
A. 12.5
B. 13
C. 13.2
D. 13.5
E. 14
Block 1, Question 4
A College runs 25 classes on Monday. Ten of the classes have an average size of 14.2 students while the other fifteen classes have an average size of 12.2 students. What is the average class size, in students, of all 25 classes run on Monday?
A. 12.5
B. 13
C. 13.2
D. 13.5
E. 14
We can use alligation method
Let the ten students in group A and other 15 in group B. The mix of 25 students is M
B..................................A
12.2...........M..............14.2
B/A= 15/10 =3/2
B..................................A
12.2....2x.....M.....3x......14.2
5x = 14.2 -12.2 =2
x=2/5 =0.4
M= 12.2+0.8 =13
Answer: B
