Exercise 8C

Solution 1 =
Amount = Principal( 1 +r/100)^n
Rs 1323 = P (1+ 5/100)^2
Rs 1323= P ( 105/100)^2
Rs 1323 × 100/105 × 100/105 = Principal
Rs 1200 = Principal

Solution 2 =

Solution 3 =

Amount = Rs 1331
Time = 3/2 = 3 half years
Rate per annum = 20% = 10%

A = P( 1 + r/100 )^n
1331 = P ( 1 + 10/100 )^3
1331 = P( 110/100)^3
1331 × 100/110 × 100/110 × 100/110 = P
1000 Rs = Principle

Solution 4 =

S.I for 2 years = P*R*2/100

C.I for 2 years = P*[(1 + r/100)^2 - 1] = P(1 + 5/100)^2) - P = P(21/20)^2 - P

C.I - S.I for 2 years = 15

C.I - S.I = 441P/400 - P - 10P/100 = (441P - 400P - 40P)/400

15 = P/400

P= 400*15 = 6000 Rs.

Hence principal(sum of money) = Rs.6000

Solution 5 =

Solution 6 = (2)

P = Rs. 3136, n = 2 years. Compound interest = Rs. 345

Compound interest = Amount - Principal

Solution 7 =

Solution 8 =

Let the principal amount be ₹ P and the rate of interest be R% per annum.

For the interest compounded half yearly:

Time = 3/2 years = 2×3/2= 3years

Rate of interest (R%) = R/2

Given: amount at the end of 3 years must become to 216P/125

A= 216P/125

A= P(1+R/00)^n

216P/125= P ( 1+ R/200)³

216/125 = ( 1+ R/200)³

(6/5)³ = ( 1+ R/200)³

(6/5) = ( 1+ R/200)

6/5-1 = R/200

(6-5)/5 = R/200

1/5 = R/200

R= 200/5 = 40%

Hence, the rate of interest (R)= 40%

Solution 9 =