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Direction : Study the following questions carefully and choose the right answer.
1
Reet invested an amount of Rs A for 2 years at 12% compound interest and received some amount of interest. Sonali invested Rs (A + 1500) for 3 years at 8% simple interest and received same amount of interest as Reet received. Find the amount that is invested by Reet.
» Explain it
B
According to the question,

A ( 1 +  12 ) 2  – A = (A + 1500) × 8% × 3
100  

A ×  112  ×  112  – A = A ×  24  + 360
100 100 100

A ×  12544  – A – A ×  24  = 360
10000 100

12544A – 10000A – 2400A  = 360
10000


144A = 3600000

A = 25000

Amount invested by Reet = Rs 25000

Hence, option B is correct.

2
Shivani has some amount of money ans she invested the money in two schemes A and B in the ratio of 2 : 5 for 2 years, scheme A offers 30% pa compound interest and scheme B offers 15% pa Simple interest. Difference between the interest earned from both the schemes is Rs.1080. How much was invested in scheme B?
» Explain it
A
Let the amount invested in scheme A is 2 × 50 = 100, the amount invested in scheme B is 5 × 50 = 250


Interest from scheme A = 100 ×  ( 1 +  30 ) 2
100  

= 169 – 100 = Rs.69

Interest from scheme B = 250 × 15% × 2

= Rs.75

Difference between interest = 75 – 69 = Rs.6 

If the difference is Rs.6., investment in scheme B = Rs.250

so the difference is Rs.1080 .,

investment in scheme B =Rs.  250  × 1080. = Rs.45000 
6

Hence, option A is correct.
3
A sum of Rs.8584 is to be paid back in 3 equal annual installments. How much is each installment if the interest is compounded annually at 14% per annum?
» Explain it
A
Given that principal P = Rs.8584

Rate R = 14%

Number of investments = 3

⇒ Value of each installment 

P
( 100 )  +  ( 100 ) 2  +  ( 100 ) 3
100 + R 100 + R   100 + R  

8584
( 100 )  +  ( 100 ) 2  +  ( 100 ) 3
100 + 14 100 + 14   100 + 14  
 

8584  = Rs. 3700
2.32

Hence, option (A) is correct.
4
Anjana lent Rs. 7000 to Sunil for 3 years and Rs. 5000 to Saurabh for 5 years on simple interest at the same rate of interest and she received Rs. 5520 from both of them as interest. Find the rate of interest.
» Explain it
C
Let the rate of interest = x%

According to the question,

7000 × 3 × x% + 5000 × 5 × x% = 5520

210x + 250x = 5520

460x = 5520

x = 12%

Rate of interest = 12%

Hence, option C is correct.
5
The compound interest on Rs 7500 in 2 years when the successive rate of interest on successive years is 8% and 10% respectively:
» Explain it
A
amount at the end of 2nd year

 = Rs7500 ( 1 +  8 )( 1 +  10 )
100 100

= Rs7500 × 1.08 × 1.10

= Rs 8910

Thus C.I. for two years = amount – principal

=   Rs8910 – Rs 7500 = Rs 1410

Hence, option A is correct.