 ## Book: NCERT - Mathematics

### Chapter: 8. Comparing Quantities

#### Subject: Maths - Class 8th

##### Q. No. 1 of Exercises 8.3

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##### Calculate the amount and compound interest on(a) Rs 10,800 for 3 years at per annum compounded annually.(b) Rs 18,000 for years at 10% per annum compounded annually.(c) Rs 62,500 for years at 8% per annum compounded half yearly.(d) Rs 8,000 for 1 year at 9% per annum compounded half yearly.(You could use the year by year calculation using SI formula to verify).(e) Rs 10,000 for 1 year at 8% per annum compounded half yearly.

(a) Here, Principal (P) = Rs. 10800, Time (n) = 3 years,

Rate of interest (R) = 12 1/2 % = (25/2)%  = Rs. 15,377.34

Compound Interest (C.I.) = A – P

= Rs. 10800 – Rs. 15377.34 = Rs. 4,577.34

(b) Here, Principal (P) = Rs. 18,000, Time (n) = 2 1/2 years, Rate of interest (R) = 10% p.a.  = Rs. 21,780

Interest for 1/2 years on Rs. 21,780 at rate of 10% = = Rs. 1,089

Total amount for 2 1/2 years

= Rs. 21,780 + Rs. 1089 = Rs. 22,869

Compound Interest (C.I.) = A – P

= Rs. 22869 – Rs. 18000 = Rs. 4,869

(c) Here, Principal (P) = Rs. 62500, Time (n) = 3/2 years = 3 years (compounded half yearly)

Rate of interest (R) = 8% = 4% (compounded half yearly)

Amount (A)  = Rs. 70,304

Compound Interest (C.I.) = A – P

= Rs. 70304 – Rs. 62500 = Rs. 7,804

(d) Here, Principal (P) = Rs. 8000, Time (n) = 1 years = 2 years(compounded half yearly)

Rate of interest (R) = 9% = (compounded half yearly)

Amount (A)  = Rs. 8,736.20

Compound Interest (C.I.) = A – P

= Rs. 8736.20 – Rs. 8000

= Rs. 736.20

(e) Here, Principal (P) = Rs. 10,000, Time (n) = 1 years = 2 years (compounded half yearly)

Rate of interest (R) = 8% = 4% (compounded half yearly)  = Rs. 10,816

Compound Interest (C.I.) = A – P

= Rs. 10,816 – Rs. 10,000 = Rs. 816

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