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  1. A certain sum of money lent out at simple interest amounts to ₹1380 in 3 years and ₹1500 in 5 years. Find the rate per cent per annum.
    1. 3%
    2. 3.5%
    3. 4%
    4. 5%
Correct Option: D

If principal = P and rate = r% per annum, then
Amount = Principle + Simple Interest

1380 = P +
P × 3 × r
.................(i)
100

1500 = P +
P × 5 × r
.................(ii)
100

S.I. for two years = 1500 – 1380 = ₹120
P × 2 × r
= 120
100

Pr
= 60...................(iii)
100

∴ From equation (i)
1380 = P + 60 × 3
⇒ P = 1380 – 180 = ₹ 1200
From equation (iii)
1200 × r
= 60
100

⇒ r =
6000
= 5% per Annum
1200

Second method to solve this question :
Here , A2 = ₹ 1500 , T1 = 3 years , A1 = ₹ 1380 , T2 = 5 years
R =
A1 - A2
× 100
A2T1 - A1T2

R =
1380 - 1500
× 100
1500 × 3 - 1380 × 5

R =
- 120
× 100
4500 - 6900

=
- 120
× 100
- 2400

R = 5%



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