A man has 390000 rupees on retirement. He gets 5000 per month as pension. his expenditure of 1st month is 5000. His expenditure increases by Rs 500 every month. When will he be bankrupt?
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1 Answers
11Expenditure is in Ap
A = 5000
d = 500
Summation Of Ap= n(2*5000 + (n-1)*500/2
Money he will have = 390000 + 5000*n
390000 + 5000*n = n(2*5000 + (n-1)*500/2
390000 = n[10000 + 500n - 500 - 10000]/2
39 * 104 = n(500n - 500]/2
78*104 = 500n2 - 500n
7800 = 5n2 -5n
1560 = n2 - n
1 ± √1+6240/2
1 + 79 /2
40 months
In 40 months he will get bankcrupt