DS - Princeton, not satisfied with OA, please discuss

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How far did Ken jump on his fifth and final attempt in the state long jump finals?

(1) On his final jump, Ken exceeded the average length of his first four jumps by 2.5 feet.
(2) Ken's final jump increased the length of his average (arithmetic mean) jump from 22.5 feet to 23 feet.

OA B
Source: — Data Sufficiency |

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by hai1 » Sat Mar 06, 2010 1:37 pm
1) is not sufficient

2)
J1+J2=J3+J4=4*22.5 ----- i
J1+J2=J3+J4+J5=5*23 -----ii

ii-i = m5= 5*23-4*22.5

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by reply2spg » Sat Mar 06, 2010 4:11 pm
In B it is not specified the average is of 4 jumps, then how B will be sufficient. However, in A, though it is not sufficient, it is clearly specified that 'en exceeded the average length of his first four jumps by 2.5 feet.'. My question about B is that how can we make sure that 22.5 is not his career average?
hai1 wrote:1) is not sufficient

2)
J1+J2=J3+J4=4*22.5 ----- i
J1+J2=J3+J4+J5=5*23 -----ii

ii-i = m5= 5*23-4*22.5

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by sarthak » Sun Mar 07, 2010 7:30 am
hi reply2spg,
it can be safely stated from the question above that the 22.5 figure is for avg of first four jumps. How else will it get increased to 23 on his fifth jump ?