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9. Commercial arithmetic
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Q5 of 59 Page 16

A sum of money triples itself in 8 years. Find the rate of interest.

Simple interest (SI)

Here,


Let Principal amount (P) = x


Time (T) = 8 years


Amount at end of 8 years = 3x


SI = 3x-x


= 2x


Rate (R) =



= 25%


∴ Rate of interest = 25%.


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3

In what period will ₹ 5,200 amounts to ₹ 7,384 at 12% per annum simple interest?

4

Ramya borrowed a loan from a bank for buying a computer. After 4 years she paid ₹ 26,640 and settled the accounts. If the rate of interest is 12% per annum, what was the sum she borrowed?

1

A person purchases the following items from a mall for which the sales tax is mentioned against:

(a) Stationery materials for ₹ 250 and sales tax of 4% there on;


(b) Electronic goods worth ₹ 2,580 and sales tax of 10% there on;


(c) Groceries worth ₹ 1,200 on which sales tax of 3% is levied;


(d) Medicines worth ₹ 200 with sales tax of 6%. Find the bill amount for each item.

2

A person buys electronic goods worth ₹ 10,000 for which the sales tax is 4% and other material worth ₹ 15,000 for which the sales tax is 6%. He manufactures a gadget using all these and sells it at 15% profit. What is his selling price?

Questions · 59
9. Commercial arithmetic
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