GATE CS 2024 Set 1 Q.4: Quantitative Aptitude

The number of coins of Rs. 1, Rs. 5, and Rs. 10 denominations that a person has are in the ratio 5:3:13. Of the total amount, the percentage of money in Rs. 5 coins is

21%

$14\frac{2}{7}\%$

10%

30%

Official answer and solution

Official answer: C
From: Official GATE 2024 answer key

Solution

Multiply the coin count ratio by the respective coin denominations to find the value ratio, then compute the percentage share of Rs. 5 coins.

Let the number of coins of Rs. 1, Rs. 5, and Rs. 10 be $5k, 3k,$ and $13k$ , respectively. Their corresponding monetary values are:

Value in Rs. 1 coins $= 1 \times 5k = 5k$
Value in Rs. 5 coins $= 5 \times 3k = 15k$
Value in Rs. 10 coins $= 10 \times 13k = 130k$

Total amount $= 5k + 15k + 130k = 150k$ . Therefore, the percentage of money in Rs. 5 coins is:

\frac{15k}{150k} \times 100\% = 10\%

Final answer

Option (C)

Common trap

Computing the percentage of the number of coins ( $3/21 = 14\frac{2}{7}\%$ ) instead of the percentage of total monetary value.

The answer is the one in the official GATE answer key. The solution is this site's own explanation.

Source

Paper: GATE 2024 Computer Science and Information Technology - Set 1 (CS1)
Question: 4 of 65
Section: General Aptitude

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