Question

Sandeep borrowed 3000 for 4 years and 8000 for 2.5 years from sonia at same rate of interest.the total interest earned by sonia is rs 2880.find rate

Answer 1

Solution :-

Let the rate of interest be x %

Scenario 1 -

Principal = Rs. 3000

Time = 4 years

S.I. = (P*R*T)/100

⇒ (3000*x*4)/100

= Rs. 120x

So, simple interest in 1st scenario is Rs. 120x

Scenario 2 -

Principal = Rs. 8000

Time = 2.5 years or 2 1/2 years

= 5/2 years

S.I. = (P*R*T)/100

⇒ (8000*x*5)/2*100)

= Rs. 200x

So, simple interest in 2nd scenario is Rs. 200x

Total interest paid by Sandeep = 120x + 200x

= Rs. 320x

Total interest earned by Sonia = Rs. 2880

∴ 320x = 2880

⇒ x = 2880/320

⇒ x = 9 %

So, the rate of interest is 9% per annum.

Answer.

Answer 2

Answer:According to first condition:

P=3000

R=x

T=4 years

Therefore,

S.I.=(P×T×R)÷100

= (3000×x×4)÷100

=120x

According to second condition:

P=8000

R=x

T=2.5 years

S.I.=(P×T×R)÷100

=(8000×x×2.5)÷100

=200x

Given-

Total interest earned by Sonia=rs2880

Therefore,

200x+120x=2880

320x=2880

X=16percent

Therefore,the rate of interest is 9 percent/annum.