Question

if P:Q=2:9 and Q :R =3:7, then the value of P:R is​

Answer 1

Answer: (b) 2:21

2/9 = 3/7 [a/b=b/c]

Make 'b' same

2/9 = 3*3/3*7

2/9 = 9/21

Therefore, a:c or in your case P:R = 2:21!

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Answer 2

Given: P:Q =2:9 and Q:R =3:7

We have to find the value of P:R.

• As we know that a ratio is an ordered pair of numbers a and b, written a / b where b does not equal 0.
• And a proportion is an equation in which two ratios are set equal to each other.

We are solving in the following way:

We have,

P:Q = 2:9 and Q:R = 3:7

We can write the above equation as:

$\Rightarrow \frac{P}{Q} \times \frac{Q}{R} \\\\\Rightarrow \frac{P}{Q} \times \frac{Q}{R}=\frac{2}{9}\times \frac{3}{7}$

Solving the above equation further equation we get,

$\Rightarrow\frac{P}{R} =\frac{2}{21}$

Hence, we get, $P:R=2:21$