Question

a certain sum amount to rupees 3120 in 3 years and to Rupees 4080 in 7 years. Find the rate % per annum​

Answer 1

Answer:

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Answer 2

Answer:

The rate is 10% per annum.

Step-by-step explanation:

Time difference = 7yrs-3 yrs=4 yrs

Difference in amount is S.I for this 4 yrs.

S.I for 4 yrs= Rs. 4080-3120= Rs.960

S.I for 3 yr = (960/4) ×3=240×3=Rs.720

For 3 yrs.,

Amount= Rs.3120

Principle= Amount - S.I

              = 3120-720=RS.2400

As we know,

S.I= (p×R×t) /100

R= (S.I ×100)/(p×t)

  = (720 ×100)/( 2400×3)

  = 72000/7200= 10 %