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  1. If the difference between the compound interest and simple interest on a sum at 5% rate of interest per annum for three years is ₹ 36.60, then the sum is
    1. ₹ 8000
    2. ₹ 8400
    3. ₹ 4400
    4. ₹ 4800
Correct Option: D

Given that , Difference = C.I. - S.I.= ₹ 36.60 , Time = 3 years , Rate = 5%
Using the given formula ,

Difference of SI and CI for 3 years =
PR(300 + R)
1003

∵ 
P × 25 × 305
= 36.60
100 × 100 × 100

⇒  P =
36.60 × 100 × 100 × 100
= ₹ 4800
25 × 305

We can find required answer with the help of given formula :
C.I.–S.I. = ₹ 36.60, R = 5%, P =?, T = 3yrs.
C.I. − S.I. = P
R
2 × 3 +
R
100100

36.60 = P
5
2 × 3 +
5
100100

36.60 = P ×
25
×
305
1002100

P =
36.60 × 100 × 100 × 100
= ₹ 4800
25 × 305

P =
36600000
= ₹ 4800
25 × 305

Tricky Approach
Difference of SI and CI for 3 years =
PR(300 + R)
1003

∵ 
P × 25 × 305
= 36.60
100 × 100 × 100

⇒  P =
36.60 × 100 × 100 × 100
= ₹ 4800
25 × 305

We can find required answer with the help of given formula :
C.I.–S.I. = ₹ 36.60, R = 5%, P =?, T = 3yrs.
C.I. − S.I. = P
R
2 × 3 +
R
100100

36.60 = P
5
2 × 3 +
5
100100

36.60 = P ×
25
×
305
1002100

P =
36.60 × 100 × 100 × 100
= ₹ 4800
25 × 305

P =
36600000
= ₹ 4800
25 × 305



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