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27 Jan 2021, 04:15
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
85% (01:43) correct
15%
(02:14)
wrong
based on 53
sessions
History
Date
Time
Result
Not Attempted Yet
The average of 15 observations is 18. Average of nine among those 15 observations is 15. What is the average of the remaining six observations?
(A) 18.75
(B) 20
(C) 22.5
(D) 24.25
(E) 25.25
(A) 18.75
(B) 20
(C) 22.5
(D) 24.25
(E) 25.25
27 Jan 2021, 06:27
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difference in average for 9 observation= 15 - 18 = -3
Using weighted average, this difference is covered by the remaining 6 observation i.e
\(\frac{18*6+3*9}{6}=18+4.5=22.5\)
Ans C
Using weighted average, this difference is covered by the remaining 6 observation i.e
\(\frac{18*6+3*9}{6}=18+4.5=22.5\)
Ans C
31 Jan 2021, 05:48
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Solution
Given
In this question, we are given that
- • The average of 15 observations is 18.
• The average of nine among these 15 observations is 15.
To find
We need to determine
- • The average of the remaining six observations.
Approach and Working out
- • Average of 15 observations = 18
- o Sum of these 15 observations = 18 × 15
- o Sum of these 9 observations = 15 × 9
• Now, sum of all 15 observations = Sum of these 9 observations + Sum of remaining 6 observations
- o 18 × 15 = 15 × 9 + Sum of remaining 6 observations
o Sum of remaining 6 observations = (18 × 15) – (15 × 9)
- = 15 × (18 – 9)
= 15 × 9
= 135
o Finally, average of remaining 6 observations = 135/6
- = 22.5
Correct Answer: Option C
