Question

Find the missing numbers on the double number line.

• A. 25 and 30
• B. 30 and 25
• C. 20 and 30
• D. 25 and 40

Answer 1

The correct option is A 25 and 30


As the double number lines represent the equivalent ratio,
Ratio at first marking = Ratio at second marking

5 : 10 = 10 : 20

$\frac{5}{10}=\frac{10}{20}$

Now, the ratio at the third marking is
$\frac{5}{10}=\frac{15}{?}$

$\underset{–}{\text{Solve for}?}$
In the first number line, when antecedant 5 is multiplied by 3 we get 15, hence we should multiply the consequent 10 by 3 in the second number line, we get 30
$\therefore$ The missing number in the ratio at the third marking is 30

Now, the ratio at the fifth marking is
$\frac{5}{10}=\frac{?}{15}$

$\underset{–}{\text{Solve for}?}$
In the second number line, when consequent 10 is multiplied by 5 we get 50, hence we should multiply the antecedant 5 by 5 in the first number line, we get 25
Hence, The missing number in the ratio at the fifth marking is 25.