Question

Mahi borrowed some amount at the rate of 10 p.m. for two and a half year and paid rupees 10,000 250 has interest find the borrowed amount by him at the total amount he paid​

Answer 1

Let the sum borrowed by Mahi be RS P and rate of interest be R%p.a

Simple interest (SI)=Rs 400,N=2 years

SI=

100

P×N×R

∴P=

N×R

SI×100

=

2×R

400×100

∴P=

R

20000

.......... (1)

Mahesh lent this sum to vishnu at the same rate for 2 years at compound interest

CI=RS 410,N=2 years

∴CI=P(1+

100

R

)

N

−P

∴CI=P[(1+

100

R

)

N

−1]

∴410=

R

20000

[(

100

100+R

)

2

−1] .......... [From (1)]

∴410=

R

20000

[

10000

10000+R

2

+200R−10000

]

∴

20000

410×R

=

10000

R

2

+200R

∴

20000

410×R

=

10000

R(R+200)

∴

20000

410×10000

=R+200

∴205=R+200

∴R=205−200

∴R=5%pa

P=

5

20000

=Rs 4000

∴ The sum borrowed by Mahesh =Rs 4000

and rate of interest +5%pa