In a family of four members, the average age of the first three members is twice that of the fourth member. The average of the four members is 35 years. If the age of the fourth member is less than from only 2 members in the family, then what is the possible age of the youngest member?
In a family of four members, the average age of the first three members is twice that of the fourth member. The average of the four members is 35 years. If the age of the fourth member is less than from only 2 members in the family, then what is the possible age of the youngest member? Correct Answer 19
Given:
The average age of four members = 35 years
The average age of the first three members = 2 × age of the fourth member
The fourth member is less than from only 2 members in the family.
Concept:
Often the average refers to the arithmetic mean, the sum of the numbers divided by how many numbers are being averaged.
Formula used:
Average age = sum of all members age/total number of members
Calculation:
Let the age of the fourth member be x.
We know that the average age of the first three members is twice that of the fourth member
Then, sum of the age of the first three members = 2x × 3 = 6x
So the sum of the age of four members
⇒ 6x + x = 7x ----(i)
But by question
The average of the four members is 35 years, then
Sum of the age of four members = 35 × 4 = 140 years ----(ii)
Now we compare both equations
⇒ 7x = 140
⇒ x = 20 years
By question, the age of the fourth member is less than from only 2 members in the family
So the possible age of the youngest member is ≤ 20 years
∴ The possible age of the youngest member is 19 years