Percentage (Railway Maths) (Part – III)

Total Questions: 50

41. Each edge of a cube is increased by 50% . Find the percentage increase in its surface area. [RRB NTPC 25/01/2021 (Morning) ]

Correct Answer: (b) 125%
Solution:

Let side of cube = 100%
Edge of a cube is increased by 50%
then side of the cube = 150 %
% increase in its surface area = 50 × 50 / 100 × 100 = 125 %

42. The price of tea has been reduced by 20%. In order to restore the original price, the new price must be increased by ? [RRB NTPC 25/01/2021 (Evening)]

Correct Answer: (a) 25%
Solution:

Let , initial price of tea
= Rs.100 , reduced by 20% = 80
Difference = 20 Rs.
Then new price must be increased = 20/80 × 100 = 25 %

43. Atulit has 100 apples. He gives 10% of the apples to Arnav, 15% of the apples to Keshav and 2/5th of the apples to Rinku. How many apples are left with Atulit after the distribution? [RRB NTPC 27/01/2021 (Morning)]

Correct Answer: (c) 35
Solution:

44. When water is changed into ice, its volume increases by 10%. If ice is changed into water, the percentage decrease in its volume will be: [RRB NTPC 27/01/2021 (Morning) ]

Correct Answer: (c) 100/11 %
Solution:

45. In the new budget, the price of petrol was risen by 20%. By how much percentage must a motorist reduce consumption of petrol so that his expenditure on it does NOT increase? [RRB NTPC 28/01/2021(Morning) ]

Correct Answer: (c)
Solution:

46. The length and breadth of a square are increased by 30% and 20% respectively. The area of the resulting rectangle exceeds the area of the square by: [RRB NTPC 28/01/2021 (Evening)]

Correct Answer: (c) 56%
Solution:

47. When the price of a gun was increased by 25%, the number of guns sold decreased by 15%. What was the effect on the sales? [RRB NTPC 28/01/2021 (Evening)]

Correct Answer: (a) 6.25% increase
Solution:

48. If the price of tea increases by 20%, by what percentage should a household reduce its consumption of tea so that the budget remains the same? [RRB NTPC 29/01/2021 (Evening) ]

Correct Answer: (a)
Solution:

49. 50% of 500 = ______ of 2500 [RRB NTPC 29/01/2021 (Evening) ]

Correct Answer: (d) 10%
Solution:

50% of 500 = ______ of 2500
⇒ 250 = x % of 2500
⇒ 250 = x × 2500/100
⇒ 250 = 25x ⇒ x = 10%

50. The population of a town increases at the rate of 10% every year. The present population is 1,000. In how many years will the population become 1,331? [RRB NTPC 29/01/2021 (Evening) ]

Correct Answer: (d) 3
Solution: