The average age of a family of 5 members is 20 years with the youngest member being 5 years old. What was the average age (in years) of the family just before the birth of the youngest member?

Correct option is C

​$$\textbf{Given Data:}\\\bullet \text{ The average age of a 5-member family } = 20 \text{ years}\\\bullet \text{ The youngest member’s age } = 5 \text{ years}\\\textbf{Step 1: Calculate the Total Age of 5 Members}\\\text{Sum of ages of 5 members} = 20 \times 5 = 100 \text{ years}\\\textbf{Step 2: Find the Total Age of 4 Members Before the Youngest Member's Birth}\\\text{Sum of ages of 4 members} = 100 - (5 \times 1) = 100 - 5 = 75 \text{ years}\\\textbf{Step 3: Find the Average Age of the 4 Members}\\\text{Average age} = \frac{75}{4} = 18.75 \text{ years}$$​​