# Sunder Pichai CEO of Google invested certain amount of money at the rate of 5% per annum compound interest, the interest compounded annually. If the d

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Sunder Pichai CEO of Google invested certain amount of money at the rate of 5% per annum compound interest, the interest compounded annually. If the difference between the interests of third year and first year is $307.50. Find the amount of money he invested. 1.$ 50,000
2. $40,000 3.$ 60,000
4. $80,000 ## 1 Answer 0 votes by (30.0k points) selected Best answer Correct Answer - Option 3 :$ 60,000

Given

Rate of Internet = 5%

Difference between the interest of third year and first year = $307.50 Formula Used S.I. = PRT/100 A = P(1 + R/100)n Calculation∶ Let the sum of money be invested be$x

Rate of interest = 5% p.a.

Now,

Interest for the first year = (x × 5 × 1) / 100 = $x/20 Interest for the 3rd year i.e. the C.I. for the third year = amount after 3 years - amount after 2 years. C.I. for the 3rd year = x(1 + 5/100)3 - x(1 + 5/100)2 ⇒ x[(21/20)3- (21/20)2] ⇒ [x × (21/20)2(21/20 - 1)] ⇒ x × 441/400 × 1/20 ⇒$ 441x/8000

Given, difference between interests of third year and first year is Rs.307.50

441x/8000 - x/20 = 307.50 = 615/2

⇒ (441 - 400)x/8000 = 615/2

⇒ 41x/8000 = 615/2

⇒ x = 615/2 × 8000/41 = $60,000 ∴ The sum of money invested by Sunder Pichai is$60,000.