Question

Raju save rs.50 in first month then the increase he saved savings by rs.100 in successide month how much has with him after one year

Answer 1

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Savings are:

200,200,200,240,280,.......up to n terms

But 200,240,280,......(n−2) terms forms an A.P

Since, sum of n terms of an AP =S n =2n

[2a+(n−1)d], where first term is a and common difference d

∴ According to question

400+ 2n−2 [2(200)+(n−2−1)40]=11040 ...... Sum =11040

⇒400+(n−2)[200+(n−3)20]=11040

⇒(n−2)[200+20n−60]=10640

⇒(n−2)(20n+140)=10640

⇒20(n+7)(n−2)=10640

⇒n 2 +5n−14=532

⇒n 2 +5n−546=0

⇒(n+26)(n−21)=0

⇒n=21

So, total time =21 months.

HOPE IT HELPS....

Answer 2

Answer:

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