Question

18. P, Q and R are three cities. The ratio of average temperature between P and Q is 11 : 12
and that between P and R is 9 : 8. The ratio between the average temperature of Q and R
is
(a) 22:27
(b) 27:22
(c) 32:33
(d) none of these
​

Answer 1

Solution

Let,

temperature of City P be p

temperature of city Q be q

and temperature of city R be r

Then,

$\tt{ \frac{p}{q} = \frac{11x}{12x} }$

so,

p = 11 x ..... eqn (1)

q = 12 x

also,

$\tt{ \frac{p}{r} = \frac{9y}{8y} }$

so,

p = 9 y ...... eqn (2)

r = 8 y

By eqn (1) and (2)

11 x = 9 y

x / y = 9 / 11 ...... eqn (3)

Now,

We have to find

q : r

so,

$\tt{ \frac{q}{r} = \frac{12x}{8y} }$

using eqn (3) to put the value of x / y

$\tt{ \frac{q}{r} = \frac{12}{8} \times \frac{9}{11} }$

so,

$\boxed{ \red{ \tt{ \frac{q}{r} = \frac{27}{22} }}}$

Hence,

correct option is ( b) 27 : 22 .