Question

When the difference between CI and SI for a certain sum for 3 years at 5% per annum is Rs. 61, find the sum.

Answer 1

Rate=5./.
Time=3yrs
C.I-S.I=Rs.61
let the principal be X
S.I= P×R×T
-------------
100
= X×5×3 = 15x
-------------- ------ ----( i )
100 100

for C.I.
t
A= P ( 1 + R )
-----
100
3 3
= x ( 1 + 5 ) = x ( 1 + 1 )
----- -----
100 20

3
= x ( 21 )
------
20
C.I.= 9261 x
----------- - x
8000

= 9261 x - 8000 x 1261 x --- ( ii )
---------------------- = ---------
8000 8000
C.I. - S.I.

= 1261 x - 15 x
-------- ----- = 61
8000 100

= 1261 x - 1200 x
------------------------ = 61
8000

= 61 x
-------- = 61
8000

x = 61 × 8000
---------------
61

= 488000
------------ = 8000
61

= Rs. 8000 Ans