UGC NET Computer Science December 2019 | Question 17

Question 17

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If 3% of (a+b) = 7% of (ab)
and 5% of (a-b) = 4% of (ab),
then what percentage of b is a?

1. 1. 47/23 %
2. 2. 23/47 %
3. 3. 4700/23 %
4. 4. 2300/47 %

Explanation

Step-by-step explanation:
Given, 3% of (a + b) = 7% of (ab)

∴ (3a + 3b)/7 = ab ........(i)

Given, 5% of (a - b) = 4% of (ab)

∴ (5a - 5b)/4 = ab .......(ii)

Now, Both equation results in ab
∴ Both are equel
∴ (5a - 5b)/4 = ab = (3a + 3b)/7
∴ (5a - 5b)/4 = (3a + 3b)/7
∴ 35a - 35b = 12a + 12b
∴ 35a-12a = 12b+35b
∴ 23a=47b
∴ b/a = 23/47
∴ a/b= 47/23
∴ a = 47b/23

To find what % of b that is equel to a
Let x% of b is equels to a
∴ (x/100)b=a
∴ (x/100)= 47b/23
∴ x=4700/23
So, Option 3 is the right answer.

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UGC NET CS December 2019 - Question 16	UGC NET CS December 2019 - Question 18