SSC MTS Model Paper 7

Question : 89 of 99

Marks: +1, -0

The difference between compound interest (compounded annually) and simple interest on a certain sum of money at 10% per annum for 2 years is 40. The sum is :

4000
3600
4200
3200

Validate

Solution:

(a) Let the principal be x.
Compound interest

= { P } [ ( 1 + { { R } }/ { 100 } \right) ^ { { t } } - 1 ]

= { x } [ ( 1 + { 10 }/ { 100 } ) ^ { 2 } - 1 ]

= x [ ( 1.1 ) ^ { 2 } - 1 ]

= x ( 1.21 - 1 ) = 0.21 x

{ Sl } = { { x } × 2 × 10 } /{ 100 } = { { x } } /{ 5 } = 0.2 { x }

Acoording to the question,

0.21 { x } - 0.2 { x } = 40

= 0.01 { x } = 40

= { x } = { 40 } /{ 0.01 } = { Rs } .4000

Method2:
Here, C .I.— S.l. = 540
r = 10% , T = 2 years, P = ?

{ C } { I } - { S } . { I } = { P } ( { { R } }/ { 100 } ) ^ { 2 }

40 = P( { 10 } /{ 100 } ) ^ { 2 }

P = R s .4000

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