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.**