# Ratio & Propotion I

Q1:

If a:b=3:2,b:c=7:15.Then find a:b:c?

Ans:

The way to find a:b:c is

a         b           c

3         2

7           15

a:b:c=3x7:7x2:2x5

=21:14:30

Q2:

Three numbers are in the ratio 2:5:8.Their HCF is 15.Find the numbers.

Ans:

The way to find numbers are multiply each ratio with HCF.

Ratio 2:5:8

HCF  15

Numbers are 2x15,5x15,8x15

ie; 30,75,120

Q3:

If a:b=5:6,b:c=3:10 and c:d=4:5.Find a:d?

Ans:

a:d means a/d.

a/d=a/b x b/c x c/d

=5/6 x 3/10 x 4/5

=1/5

ie; a:d=1:5

Q4:

Rs.828 is devided between A,B,C in the ratio 3:2:4.Then B gets?

Ans:

B got 828 x 2/3+2+4 = 828 x 2/9

ie; 184

Q5:

The ratio between number of girls and boys in a class is 5:4.Then which one of the given number will represent the number of students of that class?

38            21               48                  54

Ans:

5 +4 = 9

Here multiple of nine is 54.

Q6:

The ratio of men and women in a polling booth is 4:5.If there were 150 women more than that of man,the number of voters in the booth are?

Ans:

No. of men=4x

No. of women=5x

5x - 4x = 150

ie; x=150

The total number of voters = 5x + 4x

=9x = 9 X 150 = 1350

Q7:

a% of b is c% of d.Then find a:c?

Ans:

a% of b = c% of d

ie; a x b / 100 = c x d / 100

ie; ab=cd

ie; a/c = d/b

So a:c = d:b