Quant Quiz - Ratio

Q1)-15 litres of mixture contains 20 % alcohol and the rest water. If 3 litres of water be mixed with it, the percentage of alcohol in the new mixture would be

15 %

16(2/3)%

17 %

18(1/2) %

Ans.- B
Alcohol in 15 litres of mix= 20 % of 15 litres= 3 litres
Water in it = (15-3) L = 12 L
New quantity of mix = (15 + 3) = 18 L
Quantity of alcohol in it = 3 L
Percentage of alcohol in new mix = ( 3/18 x 100 ) = 16 (2/3) %

Q2)-20 litres of a mixture contains milk and water in the ratio 5 : 3. If 4 litres of this mixture be replaced by 4 litres of milk, the ratio of milk to water in the new mixture would be

2 : 1

7 : 3

8 : 3

4 : 3

Ans.- B
Quantity of milk in 16 L of mix = ( 16 x 5/8 ) = 10 L
Quantity of milk in 20 L of new mix = (10 + 4) L
Quantity of water in it = (20 - 14) = 6 L
Ratio of milk and water in the new mix = 14 : 6 = 7 : 3

Q3)-85 kg of a mixture contains milk and water in the ratio 27 : 7 . How much more water is to be added to get a new mixture containing milk and water in the ratio 3 : 1 ?

5 kg

6.5 kg

7.25 kg

8 kg

Ans.- A
Milk in 85 kg of mix = 85 x 27/34) = 135/2 kg
Water in it = (85 - 132/2) = 35/2 kg
Let x kg of water be added to it
Then (135/2)/(35/2 + x) =3/1
On solving x = 5 kg

Q4)-The ages of A and B are in the ratio 3 :1 . Fifteen years hence, the ratio will be 2 : 1. Their present ages are :

30 years , 10 years

45 years , 15 years

21 years , 7 years

60 years , 20 years

Ans.- B
Let the ages of A and B be 3x years and x years respectively
Then (3x + 15)/(x + 15) =2/1
x = 15
A's age = 3 x 15 =45 years
B's age = 15 years

Q5)-The average age of three boys is 25 years and their ages are in the proportion 3 : 5 : 7. The age of the youngest boy is

21 years

18 years

15 years

9 years

Ans.- C
Total age of 3 boys = 25 x 3 = 75 years
RAtio of their ages = 3 : 5 : 7
Age of the youngest = ( 75 x 3/15) = 15 years

Q6)-The speed of 3 cars are in the ratio 5 : 4: 6 .The ratio between the time taken by them to travel the same distance is

5 : 4 : 6

6 : 4 :5

10 : 12 : 15

12 : 15 :10

Ans.- D
RAtio of time taken = 1/5 : 1/4 : 1/6
= 12 : 15 : 10

Q7)-In a college , the ratio of the number of boys to girls is 8 : 5. If there are 160 girls, the total number of students in the college is

100

250

260

416

Ans.- D
Let the number of boys and girls be 8x and 5x respectively. Then , 5x=160
x = 32
Total number of students = 13x = 416

Q8)-The sides of a triangle are in the ratio 1/2 : 1/3 : 1/4 and its perimeter is 104 cm. The length of the longest side is

52 cm

48 cm

32 cm

26 cm

Ans.- B
RAtio of sides = 1/2 : 1/3 : 1/4
= 6 : 4 : 3
Largest side = ( 104 x 6/13) cm = 48 cm

Q9)-The ratio of the number of boys and girls in a school is 3 : 2. If 20 % of the boys and 25 % of the girls are scholarship holders, what percentage of the students does not get scholarship ?

56

70

78

80

Ans.- C
Let boys = 3x and girls = 2x
Number of those who do not get scholarship= (80% of 3x) + (75% of 2x) = 39x/10
Required percentage =( 39x/10 x 1/5x x 100 ) %= 78%

Q10)-In a school, 19% of boys are same in number as 1/4th of the girls.What is the ratio of boys to girls in that school ?

3 : 2

5 : 2

2 : 1

4 : 3

Ans.- B
10% of B = 1/4 G
B= 5/2 G
B/G = 5/2