# The Interests on Two Successive Years for a Sum Invested at Compound Interest Compounded Annually Are Rs 840 and Rs 940.80. Calculate the Rate of Interest and the Sum Invested. - Mathematics

Sum

The interests on two successive years for a sum invested at compound interest compounded annually are Rs 840 and Rs 940.80. Calculate the rate of interest and the sum invested.

#### Solution

For the seoond year:

A=Rs 940.80 ; P=Rs 840 ; n= 1 ;  r = ?

"A" = "P" (1 + "r"/100)^"n"

940.80 = 840 (1 + "r"/100)^1

94080 = 84000 +840 r

840 r = 10080

r = 12

Hence, rate of interest = 12°/o

For the first year:

I= Rs 840 ; r = 12 % ; n = l ; P = ?

"I" =("P" xx "r" xx "n")/100

Rs 840 = Rs ("P" xx 12 xx 1)/100

P = Rs84000/12

P = Rs 7000

The sum invested= Rs 7,000

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#### APPEARS IN

Frank ICSE Class 10 Mathematics Part 2
Chapter 1 Compound Interest
Exercise 1.4 | Q 2 | Page 12