If each term in the sum a1+a2+a3+.....+an is either 7 or 77

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Your help in this one is much appreciated..

If each term in the sum a1+a2+a3+.....+an is either 7 or 77 and the sum equals 350, which of the following could be equal to n?
A. 38
B.39
C.40
D.41
E.42

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by ajith » Wed Feb 17, 2010 12:20 pm
imane81 wrote:Your help in this one is much appreciated..

If each term in the sum a1+a2+a3+.....+an is either 7 or 77 and the sum equals 350, which of the following could be equal to n?
A. 38
B.39
C.40
D.41
E.42
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by harsh.champ » Thu Feb 18, 2010 2:56 pm
imane81 wrote:Your help in this one is much appreciated..

If each term in the sum a1+a2+a3+.....+an is either 7 or 77 and the sum equals 350, which of the following could be equal to n?
A. 38
B.39
C.40
D.41
E.42
In short I would say after adding each term the no. in the units place will go in a series like 7,4,1,8... which becomes 0 for the 10th term.Hence,the answer has to be a multiple of 10. So,C.
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by shashank.ism » Sun Feb 21, 2010 8:48 pm
check the appropriate solution in this thread..
https://www.beatthegmat.com/if-each-term ... 13856.html
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