a certain amount of money was deposited in to a bank account having a simple interest rate of 5%.if the total amount after 4 years was ₹1,500 how much was the amount deposited initially?for the same initial amount, how should the interest rate increase such that the simple interest would amount to ₹400?
Answers
write as:
A - P = \frac{PRT}{100}A−P=
100
PRT
\implies 1500 - P = \frac{P\times 5\times 4}{100}⟹1500−P=
100
P×5×4
\implies 150000 - 100P = P\times 5\times 4⟹150000−100P=P×5×4
\implies 150000 - 100P = 20P⟹150000−100P=20P
\implies 100P + 20P = 150000⟹100P+20P=150000
\implies 120P = 150000⟹120P=150000
\implies P = \frac{150000}{120}⟹P=
120
150000
\implies \bold{P = Rs.\:1250}⟹P=Rs.1250
Step-by-step explanation:
It is given that the man deposited Rs 10000 in a bank at the rate of 5% simple interest annually. Since, the simple interest is added every year, the amount in every year is a term in arithmetic progression.
Formula for Simple Interest I=
100
P⋅T⋅R
∴ Interest for each year =
100
5
×Rs 10000=Rs 500
Interest for each year is the common difference.
Formula for n
th
term in an AP t
n
=a+(n−1)d
Amount in 15
th
year =10000+14(500)
=17000
Amount after 20 years, which is amount in 21
st
year=10000+20(500)
=20000