Question

If rs 640 amounts to 768 in 2 years 6 months,what will 850 amount to in 3 years at the same rate per cent per annum?

Answer 1

given P1= principle=rs640
and amount = A1 = rs768
therefore, simple interest = SI1 = amount - principal
= A1-P1 = rs768 - rs640
= rs128
Time= T1 = 2yrs. and 6 months = 2.5 yrs.
S.I= P×R×T/100
therefore, Rate = R1= SI1×100/P1×T1
= rs128×100/rs640×2.5
=rs12800/rs1600
= 8%

principle given again = P2 = rs850
rate% we have find out =R2= 8%
time given = T2 = 3 yrs.
SI2 = P2 × R2 × T2 /100
= 850×8×3/100
= rs204
A = P2 + SI2
= 204+850
= rs 1054

Answer 2

p = 640
A = 768
T = 2 years and 6 month
SI = A-P
= 768- 640
= 128
rate = SI * 100 / P * T
= 128 * 100 / 640 * 2.5
= 8%
= SI = P * R * T / 100
= 850 * 8 * 3