9x, x + 6, 7x – 3 and y are in proportion when x = 3. Find the value of y.

Correct option is D

Given:

9x, x + 6, 7x – 3 and y are in proportions

x = 3

Formula Used:

If 4 numbers a, b, c and d are in proportional then:

a : b : : c : d and $$a \times d = b \times c$$​

or  $$d = \frac{b\times c}{a}$$​​

Solution:

9x, x + 6, 7x – 3 and y

​$$y= \frac{(x+6) \times (7x-3)}{9x}$$​

When x = 3

y = $$\frac{(3+6) \times 7(3)-3}{9(3)}$$​​

$$= \frac{9 \times 18}{27}$$​​

= 6