IBPS SO Prelims Exam Model Paper 5

Case(1): When interest is calculated yearly, rate% = 10%
Case(2): When interest is calculated half yearly, rate% is halved and time is doubled
So, rate% =

10

2

= 5%, time = 2 years
S.I = P × R ×

T

100

⇒ S.I =

(P×10×1)

100

=

P

10

C.I = P{(1+

5

100

)2 – 1}
⇒ C.I = P{(

21

20

)2 – 1}
⇒ C.I = P(

41

400

)
Now, difference between C.I and S.I = 180
⇒ P(

41

400

) –

P

10

= 180
⇒ P(

1

400

) = 180
⇒ P = 180 × 400 = Rs. 72,000
Effective rate% = 5 + 5 + {5 ×

5

100

} = 10.25%
Difference in rates = 10.25 - 10 = 0.25%
According to the question,
0.25% of sum = Rs. 180
∴ Sum = (180/0.25) x 100 = Rs. 72,000