# A certain amount of money was put in the bank. A year later, 0.25 of the initial amount was withdrawn from the account

A certain amount of money was put in the bank. A year later, 0.25 of the initial amount was withdrawn from the account, and a year later, the deposit amounted to 0.935 of the original amount. Find bank interest.

Let S be the amount of money deposited in the bank.
р% – interest that the bank calculates per year.
Account status after a year:
S + S * p / 100;
Account balance after withdrawing 25% of the original amount:
S + S p / 100 – S 25/100 = 0.75 S + S p / 100;
Account status after two years:
(0.75 S + S p / 100) + (0.75 S + S p / 100) p / 100 = 0.935S.
Reduce the expression by S and multiply by 10000.
7500 + 100p + 75p + p ^ 2 = 9350;
7500 + 175 p + p ^ 2 – 9350 = 0;
p ^ 2 + 175 p – 1850 = 0;
find the roots by Vieta’s theorem.
p1 p2 = -1850;
p1 + p2 = -175;
p1 = -185 – does not meet the conditions of the problem.
p2 = 10.
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