Question

7. What principal will amount to 9,856 in two
years, if the rates of interest for successive
years are 10% and 12% respectively ?​

Answer 1

Let the Principal was P

for first year, R = 10%

Interest = PTR/100 = P×1×10/100 = 0.1P

Amount at the end of 1st year = P + 0.1P = 1.1P

For 2nd year,

Principal = 1.1P

R = 12%

Interest = PTR/100 = 1.1P×1×12/100 = 0.132P

Amount at the end of 2nd year = 1.1P + 0.132P = 1.232P

It is given that amount is 9856

⇒1.232P = 9856

⇒ P = 9856/1.232

⇒ P = Rs. 8000

Principal was Rs. 8000

Answer 2

Answer:

Let Principal =

′

P

′

Amount =Rs9856

R

1

=10%

R

2

=12%

T=2 year

A=P(1+

100

R

1

)(1+

100

R

2

)

⇒9856=P(

70

11

)(

25

28

)

⇒P=

11×28

9856×10×25

=8000

Hence, Principal is Rs8000.