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01 Nov 2019, 07:53
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B
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Difficulty:
65%
(hard)
Question Stats:
48% (01:19) correct
52%
(01:21)
wrong
based on 593
sessions
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Set V consists of 2 distinct positive values. What is the standard deviation of set V?
(1) The mean of the set is 10.
(2) The range of the set is 10.
Are You Up For the Challenge: 700 Level Questions
(1) The mean of the set is 10.
(2) The range of the set is 10.
Are You Up For the Challenge: 700 Level Questions
01 Nov 2019, 08:17
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Bunuel
Let the 2 distinct values of the set = {a, b} and a < b
(1) The mean of the set is 10.
Many values of {a, b} are possible = {1, 19} or {2, 18} or {2.5, 17.5} so on ...
--> We cannot find exact value of standard deviation --> Insufficient
(2) The range of the set is 10.
--> Many values of {a, b} are possible = {1, 11} or {2, 11} or {2.5, 12.5} so on ...
--> b = 10 + a
--> Set = {a, 10 + a}
Step 1: Mean = (a + 10 + a)/2 = 5 + a
Step 2: Deviations from Mean = {a - (5 + a), 10 + a - (5 + a)} = {-5, 5}
Step 3: Standard deviation = \(\sqrt{\frac{((-5)^2 + 5^2)}{2}} = \sqrt{\frac{50}{2}}= 5\) --> Sufficient
IMO Option B
General Discussion
02 Nov 2019, 05:41
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Statement 1 : the mean alone provides us insufficient information to find the SD
Statement 2 : Every set of 2 distinct numbers with a range of 10 will have the same SD=25. Sufficient
Statement 2 : Every set of 2 distinct numbers with a range of 10 will have the same SD=25. Sufficient
