n=10
1- 2n is 1-20
20(21)/2
121
sub n=10
A)10*11=false
B)5*21 -false
C)10*21-true
D)20*11-false
E)20*21-Fa;lse
OA C
confirm please
Vishu
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sum of the integer from 1 to 2n
Source: Beat The GMAT — Problem Solving |
Mals24 solution is good.
If we have problems we can pick numbers
lets say 1,2,3 here n=3 sum is 6
2n= 6 i.e 6 numbers 1,2,3,4,5,6 Sum = 21
Only choice that will work is C) N(2N+1)
3(6+1) = 21
Done C)
If we have problems we can pick numbers
lets say 1,2,3 here n=3 sum is 6
2n= 6 i.e 6 numbers 1,2,3,4,5,6 Sum = 21
Only choice that will work is C) N(2N+1)
3(6+1) = 21
Done C)
