Number Series Model Questions Set 1 Section-Wise Topic Notes With Detailed Explanation And Example Questions

Question : 1

A vessel of 80 litre is filled with milk and water. 70% of milk and 30% of water is taken out of the vessel. It is found that the vessel is vacated by 55%. Find the initial quantity of milk and water.

a) 30, 50

b) 60, 20

c) 20, 60

d) 50, 30

e) None of these

Answer: (d)

Here, the % values of milk and water that is taken from the vessel should be taken into consideration.

⇒5 : 3

Ratio of milk to water = 5 : 3

∴ quantity of milk = ${80}/{5 + 3}$ × 5 = 50 litres

and quantity of milk = ${80}/{5 + 3}$ × 3 = 30 litres

Question : 2

Gold is 19 times as heavy as water and copper 9 times. In what ratio should these metals be mixed so that the mixture may be 15 times as heavy as water?

a) 3 : 2

b) 4 : 5

c) 1 : 2

d) 2 : 3

e) None of these

Answer: (a)

∴ Gold : Copper = 6 : 4 = 3 : 2

Question : 3

In what ratio must water be mixed with milk costing Rs. 12 per litre to obtain a mixture worth of Rs. 8 per litre?

a) 2 : 1

b) 3 : 2

c) 1 : 2

d) 2 : 3

e) None of these

Answer: (c)

By the rule of alligation:

Ratio of water to milk = 4 : 8 = 1 : 2

Question : 4

What should come in place of the question mark (?) in the following number series?

2, 4, ?, 16, 32

a) 10

b) 12

c) 6

d) 8

e) None of these

Question : 5

What should come in place of the question mark (?) in the following number series?

10, 14, 25, 55, 140, (?)

a) 398

b) 396

c) 386

d) 388

e) None of these

Question : 6

What should come in place of the question mark (?) in the following number serie?

9, 27, 36, 63, 99, ?

a) 167

b) 162

c) 151

d) 152

e) 157