Question

If a:b = 6:5 and b:c=4:9, find a:c

Answer 1

Step-by-step explanation:

To find a : b : c, b is made same in both the ratios. L.C.M of 4 and 5 is 20

a:b=

4

3

=

4×5

3×5

=

20

15

b:c=

9

5

=

9×4

5×4

=

36

20

∴ a:b:c=15:20:36

Answer 2

Answer:

a : b = 5 : 9

b : c = 4 : 7

Observe that the figures against b are 9 and 4 .

Find LCM of 9 and 4. This is 36.

Now make figures in both ratios such that figure against b is 36.

Therefore a : b = (Multiply by 4) 5x4 : 9x4 = 20 : 36

B : c = (multiply by 9) 4x9 : 7x9 = 36 : 63

When figure against b is made same (as b =36 above),

Ratio a : b : c = 20 : 36 : 63

and a :c = 20 : 63