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16 Mar 2016, 18:27
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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:
88% (01:29) correct
13%
(01:15)
wrong
based on 82
sessions
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If the average (arithmetic mean) of 9 numbers is 325, what is the median of them?
1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500
* A solution will be posted in two days.
1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500
* A solution will be posted in two days.
17 Mar 2016, 07:28
Kudos
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Sum of 9 numbers = 325(10 - 1) = 2925
Median = 5th number
St1: Sum of 4 smallest numbers = 500
Sum of 5 larger numbers = 2425. So we cannot determine the exact value of the median
St2: Sum of 4 largest numbers = 2000
Sum of 5 smallest numbers = 925. Cannot determine the median value
Combine St1 and St2: Median = 2925 - 2000 - 500 = 425
Answer: C
Median = 5th number
St1: Sum of 4 smallest numbers = 500
Sum of 5 larger numbers = 2425. So we cannot determine the exact value of the median
St2: Sum of 4 largest numbers = 2000
Sum of 5 smallest numbers = 925. Cannot determine the median value
Combine St1 and St2: Median = 2925 - 2000 - 500 = 425
Answer: C
19 Mar 2016, 23:05
Kudos
Bookmarks
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
If the average (arithmetic mean) of 9 numbers is 325, what is the median of them?
1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500
In the original condition, there are 9 variables, which should match with the number of equations. So you need 9 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make E the answer.
When 1) & 2), s1+s2+s3+s4+Median+L1+L2+L3+L4=9*325 is derived. From s1+s2+s3+s4=4*125 and L1+L2+L3+L4=4*500, you can figure out Median in a unique way, which is sufficient. Therefore, the answer is C.
If the average (arithmetic mean) of 9 numbers is 325, what is the median of them?
1) The average (arithmetic mean) of the 4 smallest numbers of them is 125
2) The average (arithmetic mean) of the 4 largest numbers of them is 500
In the original condition, there are 9 variables, which should match with the number of equations. So you need 9 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make E the answer.
When 1) & 2), s1+s2+s3+s4+Median+L1+L2+L3+L4=9*325 is derived. From s1+s2+s3+s4=4*125 and L1+L2+L3+L4=4*500, you can figure out Median in a unique way, which is sufficient. Therefore, the answer is C.
