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13. Harry Potter was very impressed with the education he received at Hogwarts.

ID: 2804747 • Letter: 1

Question

13. Harry Potter was very impressed with the education he received at Hogwarts. He would like to give them a meaningful gift, but doesn't have a lot of money right now, fighting evil wizards and new wands has drained his bank account. He decides that he will open a new account at Gringotts for this purpose. Gringotts has promised to pay him 9% interest compounded annually. Harry will leave this gift to Hogwart's upon his death. Assuming that he lives another 70 years, deposits $ 1,440 in the account today, and the account earns 9% interest per year, how much will Hogwart's get in 70 years? (rounded to the nearest 1,000) a. $1,000,000 b. $67,000 c. $187,000 d. $600,000

Explanation / Answer

Formula for compound interest:

A = P x (1+i/n)t

Where,
   P = principle amount = $ 1,440

   A = Amount after maturity
   i = Interest rate = 9 % or 0.09 p.a.

   n = No. of compounding frequency in a year = 1
   t = number of periods = 70

A = $ 1,440 x (1 + 0.09)70

   = $ 1,440 x (1.09)70

   = $ 1,440 x 416.7300862

   = $ 600,091.3241 or $ 600,000    [on rounding to nearest 1000]

Hence option “d. $ 600,000” is correct answer.

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