Question

if a:b =3:5, b:c = 6:7 find a:b:c​

Answer 1

Topic

Ratio

Given

a : b is 3 : 5 and

b : c is 6 : 7

To Find

a : b : c

Solving

Technique 1

To solve such type of question we need to find a common value of 'b' for both given ratios.

To find the common value, take denominator part of ratio in which 'b' is in denominator and take numerator part of ratio in which 'b' is in numerator.

LCM of 5 and 6 is 30.

Now, we need to write both ratio such that 30 is taking part in ratio.

So, we can write

a / b = 3 / 5 = 18 / 30 and

b / c = 6 / 7 = 30 / 35

Now, multiply both the equation.

On multiplying, we get

a / c = 18 / 35 that means

a : c = 18 : 35 and

a : b = 18 : 30

So,

a : b : c is same as

18 : 30 : 35

Technique 2 ( Shortcut )

a : b = 3 : 5

Now, divide a and b by denominator that is 5.

a : b = 3/5 : 1

Similarly,

b : c = 6 : 7

Now, divide b and c by numerator that is 6.

b : c = 1 : 7/6

Now, we are having same values of 'b'.

So,

a : b : c is same as

3/5 : 1 : 7/6

Now, multiply by 30 in whole obtained ratio.

30*(3/5) : 30 : 30(7/6)

18 : 30 : 35

Answer

So, the ratio a : b : c is equal to

18 : 30 : 35

Answer 2

Answer:

according to the question,

a:b=3:5

b:c=6:7

b has two values 5 and 6

so we will take out the LCM of 5,6 which is 30

a:b

a/b=3/5=3*6/5*6=18/30

b:c

b/c=6*5/7*5=30/35

hence,

a:b:c=18:30:35

$Hope\:it\:helps\:you....$