RRB NTPC - Ratios and Proportions (114 Questions with Explanation)

1.

Eight people are planning to share equally the cost of a rental car. If one person withdraws from the arrangement and the others share equally the entire cost of the car, then the share of each of the remaining persons increased by

   A.) One-seventh
   B.) Seven-eighths
   C.) One-eighth
   D.) One-ninth

Answer: Option 'A'

When there are 8 people, the share of each person is 1/8
When there are 7 people, the share of each person is 1/7
Increase in the share of each person is 1/7 - 1/8 = 1 / 56 ,
Which is 1/7 of 1/8 of the original share of each person.

2.

If A:B = 3:2 B:C= 4:3 then A:B:C=?

   A.) (6:4:3)
   B.) (3:4:3)
   C.) (3:2:3)
   D.) (3:2:1)

Answer: Option 'A'

(6:4:3)

3.

Two numbers are respectively 20% and 50% more than a third number. The ratio of the two numbers is:

   A.) 05:07
   B.) 04:05
   C.) 02:07
   D.) 02:05

Answer: Option 'B'

Let the third number be x.
Then, first number = 120% of x = 1.2x = (6x/5) Second number = 150% of x = 1.5x =(3x/2)
Ratio of first two numbers = (6x/5) : (3x/2) = 12/15 = 4/5
Ratio is 4 : 5

4.

A bag contains 5p,10p and Rs20p coins in the ratio of 4:2:1 respectively. If the total money in the bag is Rs.30/-. Find the number of 5p coins in that bag? 

   A.) 100 coins
   B.) 150 coins
   C.) 200 coins
   D.) 250 coins

Answer: Option 'C'

5paisa : Rs.10/- : Rs.20/- = 4 : 2 : 1  ---> coins ratio   
=  1 : 1 : 1 ----> money ratio 
3 ---> 30 
1 ---> Rs.10/- × 20 coins ( 1/- = 5paisa × 20 cions ) 
Rs.10/-  = 200 coins(5paisa)

5.

20 boys and 25 girls form a group of social workers. During their membership drive, the equal number of boys and girls joined this group. How many members does the group have now, if the ratio of boys to girls is 7 : 8 ?

   A.) 65
   B.) 75
   C.) 80
   D.) 85

Answer: Option 'B'

Let x girls and x boys join this group.
Then (20+x) / (25+x) = 7/8 => 160 + 8x = 175 + 7x => x = 15 Boys = 20 + 15 = 35 Girls = 25 + 15 = 40, total = 35 + 40 = 75

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