Question

6. Find the fourth proportional to the numbers:
(i) 5, 7, 30
​

Answer 1

Answer:

Let the fourth number be x

Then

=5:7::30:x

We know that

product of extremes = product of means

∴ 5×x=7×30

5x=210

x=210/5

x=42

Hence, x=42

Answer 2

Let the fourth number be x

Then, = 5: 7:: 30: x

We know that,

Product of extremes = product of means

∴ 5 × x = 7 × 30

=> 5x = 210

=> x = 210/5

=>x = 42

Hence, x = 42