Question

if a:b is 3:4 and b:c is 2:5, find a:b:c

Answer 1

Answer:

Step-by-step explanation:

We are given with two simple ratios

a:b=2:3,

b:c=4:5

When we want the combined ratio of these kind of ratios like a:b:c, we do have a small trick.

In a:b:c the ratio component of ‘a’ will be the product of compnent of ‘a’ in a:b and component of ‘b’ in b:c I.E., 2*4=8. a=8.

Component of ‘b’ will be product ‘b’ components in both the ratios I.E., 4*3=12. b=12

Component of c will be product of Component of b in a:b and c component in b:c I.E., 5*3=15. C=15

Answer 2

Given

a : b = 3 : 4

b : c = 2 : 5

To Find

a : b : c

Solution

We have been given the fact that a: b = 3:4

That is a = 3 and b = 4

We have also given b: c = 2: 5

That is again b =  2 and c = 5

There is a simple technique to solve this problem.

let us write the given factors underneath each assigned alphabets row wise as shown below.

a   b   c

3   4

   2    5

Now let us fill the remaining portion as shown below. In the first row, write the value of 'b' underneath 'c' and in the second row write the value of 'b' underneath 'a'.

a  b  c

3  4   4

2  2   5

Now multiply the numbers downwards

That is, a = 3×2

b = 4 × 2

c = 4 × 5

Therefore a:b:c = 6:8:20 or 3:4:10