Question

A sum when reckoned at 7 1/2 % per annum amounts to 3920 in 3 years . Find Sum
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Answer 1

Answer:

p=Axloo/100+rt

=3920x100/100+7.5x3

=3920x100/122.5=3200

Sum=Rs3200. Ans

Answer 2

Given :

Amount (A) = Rs. 3920

Rate = 7$\frac{1}{2}$ % = $\frac{15}{2}$%

Time (T) = 3 years

To Find :

The Principal amount (P)

Solution :

The formula for Simple Interest is

Simple Interest (SI) = $\frac{P*R*T}{100}$

Where, P = Principle; R = Rate and T = Time

SI = Amount (A) - Principle (P)

SI =   3920 - P

∴ Simple Interest (SI) =  $\frac{P*R*T}{100}$

⇒   3920 - P              =  $\frac{P * \frac{15}{2} * 3 }{100}$

⇒   3920 - P              =  $\frac{P*15*3}{200}$

⇒  784000 - 200P    =   45P

⇒       245P                =   784000

∴            P                   =  3200

Therefore, the sum of money (Principal) is Rs. 3200