The average age of 6 members of a family is 20 years. If the age of the servant is included, then the average age increases by 20%. What is the age of the servant?
Answer & explanation
Correct answer: option 4
The average of family's age = $\frac{sum\;of\;ages\;of\;all\;members}{6}$
Sum of ages of all members = 20 x 6 = 120
Let the age of the servant be $x$ years,
average increases by 20%, new average = 24
Thus, $\frac{120+x}{7}$ = 24
$120 + x = 168$
$x$ = 48 years