A number is increased by 40% and then decreased by 40%. If the resulting number is 84, find the original number. MCQ with Answer and Explanation

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A number is increased by 40% and then decreased by 40%. If the resulting number is 84, find the original number.

A. 90

B. 110

C. 100

D. 120

Answer: Option C

Solution (By JKSSB Mock Tests)

1.4 × 0.6 = 0.84, 0.84x=84 → x=100.

This question belongs to: Maths Percentage

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Practice More Percentage Questions

Question #1

Side of square increased 10%. % increase in area:

A. 20%

B. 21%

C. 25%

D. 22%

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Correct Answer: Option B

Explanation:
Area multiplier = 1.1² = 1.21, increase 21%.

This question belongs to: Maths Percentage

Question #2

The price of an article is increased by r% and then decreased by r%. If the net decrease is 1%, find r.

A. 5

B. 10

C. 8

D. 12

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Correct Answer: Option B

Explanation:
1 - r²/10000 = 0.99 → r² = 100 → r = 10.

This question belongs to: Maths Percentage

Question #3

The ratio of the ages of A and B is 5:7. After 10 years, the ratio will be 7:9. Find the present age of A.

A. 20 years

B. 35 years

C. 30 years

D. 25 years

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Correct Answer: Option D

Explanation:
Let ages 5x, 7x. (5x+10)/(7x+10) = 7/9 → 45x+90 = 49x+70 → 4x=20 → x=5, A=25.

This question belongs to: Maths Percentage

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