Compound Interest
- If the difference between the compound interest and simple interest on a sum of money at 5% pa for 2 yr is ₹ 16, then find the simple interest ?
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Given, CI - SI = 16, R = 5%, n = 2 yr and SI = ?
According to the formula,
CI - SI = (SI x R)/200
⇒ 16 = (SI x 5)/200Correct Option: D
Given, CI - SI = 16, R = 5%, n = 2 yr and SI = ?
According to the formula,
CI - SI = (SI x R)/200
⇒ 16 = (SI x 5)/200
⇒ 16 = SI/40
∴ SI = ₹ 640
- A sum, at the compound rate of interest, becomes 21/2 times in 6 yr. The same sum becomes what times in 18 yr ?
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If sum is P, then P becomes 5P/2 in 6 yr.
5P/2 becomes 25P/4 in 12 yr.
25P/4 becomes 125P/8 in 18 yr.Correct Option: C
If sum is P, then P becomes 5P/2 in 6 yr.
5P/2 becomes 25P/4 in 12 yr.
25P/4 becomes 125P/8 in 18 yr.
The sum becomes 125/8 times in 18 yr.
- The cost price of an LCD TV set is ₹ 100000. If its price value depreciates at the rate of 10% pa. then what will be the price at the end of 3 yr?
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Given P = ₹ 100000, R = 10%, n = 3 yr
According to the formula,
Price of LCD TV set after 3 yr. = P(1 - R/100)n
= 100000 (1 - 10/100)3Correct Option: D
Given P = ₹ 100000, R = 10%, n = 3 yr
According to the formula,
Price of LCD TV set after 3 yr. = P(1 - R/100)n
= 100000 (1 - 10/100)3
= 100000(90/100)3
= 100000 x (9/10) x (9/10) x (9/10)
= ₹ 72900
- A sum of ₹ 400 amounts to ₹ 441 in 2 yr. What will be its amount, if the rate of interest is increased by 5% ?
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According to the given condition.
441 = 400 (1 + R/100)2
⇒ 441/400 = (1 + R/100)2
⇒ (21/20)2 = (1 + R/100)2
⇒ 21/20 = 1 + R/100
⇒ (21/20) - 1 = R/100
⇒ R/100 = 1/20
∴ R = 5%
∴ new rate = 5 + 5 = 10%
∴ Amount = 400 (1 + 10/100)2Correct Option: A
According to the given condition.
441 = 400 (1 + R/100)2
⇒ 441/400 = (1 + R/100)2
⇒ (21/20)2 = (1 + R/100)2
⇒ 21/20 = 1 + R/100
⇒ (21/20) - 1 = R/100
⇒ R/100 = 1/20
∴ R = 5%
∴ new rate = 5 + 5 = 10%
∴ Amount = 400 (1 + 10/100)2
= 400 x (11/10) x (11/10)
= ₹ 484
- The population of a city increases at the rate of 5% pa. If the present population of the city is 185220, then what was its population 3 yr ago?
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Given, P = 185220 R = 5% (increases) and n = 3 yr
According to the formula,
Population n yr ago = P/(1 + R/100)n
= 185220/(1 + 5/100)3Correct Option: C
Given, P = 185220 R = 5% (increases) and n = 3 yr
According to the formula,
Population n yr ago = P/(1 + R/100)n
= 185220/(1 + 5/100)3
= 185220/[(21/20) x (21/20) x (21/20)]
= [185220 x 20 x 20 x 20] / [21 x 21 x 21]
= 20 x 20 x 20 x 20
= 160000