Question

Find the third proportional of 36 and 42.

• A. 49
• B. 38
• C. 42
• D. 56

Answer 1

Answer:

A. 49

The third proportional to two numbers (a) and (b) is a number (c) such that:
a : b = b : c

Step 1: Apply the formula

$36 : 42 = 42 : c$

This means:
$\frac{36}{42} = \frac{42}{c}$

Step 2: Cross multiply

$36c = 42 \times 42$
36c = 1764
$c = \frac{1764}{36}$
c = 49
Final Answer: 49