this is a ques from the test forum
a man has Rs390000 on retirement He gets Rs5000 per month as pension His expenditure of first month is Rs5000 and increases by Rs500 every month When he will be bankrupt
Please solve it
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2 Answers
11For the first series, a1=Rs390000 d1=+ Rs5000
For the second series, a2=- Rs5000 d1=- Rs500 (since expenditure decreases the net balance)
Find nth term and find n........that is number of months [4]
62His total pension at the end of n months is n.5000
his total expenditure in the rth month is
5000+500(r-1)
His total expenditure till the nth month
= Σ{5000+500(r-1)}
=4500n+500n(n+1)/2
Hence His value at the end of n months =
390000 + n.5000 - {4500n+500n(n+1)/2} = 0 in the month when he goes bankrupt.
390000 + n.500 - 500n(n+1)/2 =
780 = n(n-1)/2
1560 = n(n-1)
thus n=40 months