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by samirpandeyit62 » Sat Oct 06, 2007 2:16 am
If the average of 6 numbers is 20, how many of the numbers are equal to 21?

(1) Three of the numbers are equal to 19.
(2) Three of the numbers are less than 21.

stmt 1: other 3 need to sum up to 63 so they can be 21,21,21 or 20,20,23 or 21,22,20 ... so INSUFF

stmt2 : the three can have any combination summing upto 60 or less, similary the other can be anything so INSUFF

combine:

if three nos are = 19 & three are less than 21, then these three must be the one'e eqaul to 19, otherwise the mean will decrease
again the remainig three may be anything as stmt 1 so INSUFF

ans should be E
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Samir
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Source: — Data Sufficiency |
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by samirpandeyit62 » Sat Oct 06, 2007 4:24 am
If the average of 6 numbers is 20, how many of the numbers are equal to 21?

Three of the numbers are less than 21.

given this information we can assume that the three nos are

19,19,19 so other 3 are 21,21,21

18, 16,20 so other 3 can be 21,21,24

10,15,17 so other 3 can be 30,25,23

now here how can we find exact nos of 21's
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by Bhandaripreeti » Sat Oct 06, 2007 4:38 am
If the average of 6 numbers is 20, how many of the numbers are equal to 21?

(1) Three of the numbers are equal to 19.
(2) Three of the numbers are less than 21

First St-

19,19,19,21,21,21,21
19,19,19,18,21,24
Not Suff

10,10,10,30,30,30
19,19,19,21,21,21
Not Sufficient

Combining the two - First set of values 19,19,19 , since the second st restricts the value of other 03 numbers to greater than or equal to 21, the only possible values are 21,21,21
19,19,19,21,21,21

If we try another set values it wont hold good
19,19,19,22,21,20- the last value will have to be less than21 which will violate st 2
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by samirpandeyit62 » Sat Oct 06, 2007 4:39 am
A correction, the ans should be C,

coz if we combine the 2 stmts, then we have

19,19,19,21,21,21 is the only combination which satisfies

as other 3 cant be 20,22,21.... etc(that will make 4 or mor nos less than 21)

(1) Three of the numbers are equal to 19.
(2) Three of the numbers are less than 21.
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Samir
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by samirpandeyit62 » Sat Oct 06, 2007 4:49 am
Hi Guest,
Are u sure that there is no data missing in the question, coz I dont think a rational explanation can be given for B.
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by josephcho77 » Sat Oct 06, 2007 6:35 am
Hey Guest,

The answer can't be "B" for this question if you don't miss something.
OA is not always correct
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