Question

1. What rate gives Rs.100 as interest on a sum of Rs.1000 in 2 years.

Answer 1

Given:-

• Rs.100 as interest on a sum of Rs.1000 in 2 years.

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To find:-

• Interest rate.

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Solution:-

According to the question

→ Interest = principal × rate of interest × no. of years

→ 100 = 1000 × (R) × 2

→ 100 = 1000 × R × 2

→ 100 = 2000 R

→ 100/2000 = R

→ 0.05 = R

→ R = interest rate/100

→ 0.05 = interest rate/100

→ 0.05 × 100 = interest rate

→ interest rate = 5%

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Hence,

• the interest rate is 5%.

Answer 2

$\red{\sf{\star\;Given :-}}$

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• Principal = ₹1000
• Interest = ₹100
• Time = 2 years

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$\green{\sf{\star\;To\; Find :-}}$

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• The rate of interest

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$\orange{\sf{\star\;Solution :-}}$

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• Amount = Principal + Interest
• = ₹(1000 + 100)
• = ₹1100

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We know that,

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

$I\: =\: {\dfrac{P \times R \times T}{100}}$

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• On inserting the values in the formula

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We get ,

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$100\: =\: {\dfrac{1000 \times R \times 2}{100}}$

$\implies R\: =\: {\dfrac{100 \times 100}{1000 \times 2}}$

=> R = 5% ✔

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Thereforeis, rate of interest is 5%

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Short-hands Used :-

• P = Principal
• R = Rate
• T = Time
• A = Amount
• I = Interest

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