Question

in how many years will rupees 300 amount to Rupees360 at 4%p.a. simple interest?

Answer 1

Simple Interest
In profit and loss chapter, we have taken that a merchant is doing business with us so that he makes profit on his investment.

In Simple interest problems, we ourselves do business with a bank.  i.e., we keep our money in the bank so that bank gives us interest (Profit)  at certain interest rate (Profit %), which is profit for us.  So all the formulas in profit and loss are useful in this chapter too.

We know that Profit = CP × (profit %)
Profit %= ProfitCost price×100ProfitCost price×100

Simple interest formula:Simple interest for 1 year = Principal × (Interest %) = P × (R%)
If simple interest for more than 1 year the Simple interest = P×R%×T=SIP×R%×T=SI
Interest % = InterestPrincipal×100=SIP×100InterestPrincipal×100=SIP×100

Simple interest is directly proportional to the principal, rate of interest, and time.

Answer 2

Hi ,

Principal = P = Rs300

Amount = A = Rs 360

Rate of interest = r = 4%

Time = t years

A = P ( 1 + TR/100 )

360 = 300 ( 1 + 4t/100 )

360/300 = 1 + 4t/100

36/30 - 1 = 4t/100

( 36 - 30 ) /30 = 4t/100

6/30 = t/25

( 6 × 25 ) / 30 = t

25 / 5 = t

5 = t

t = 5 years

I hope this helps you.

:)