Question

Q14. The average age of the family of 7 members is 23 years. If the age of
the youngest member be 8 years, then the average of the family at the
birth of the youngest was
O 18 years
O 20 years
O 17.5 years
O
15 years​

Answer 1

Answer:

15 years

Step-by-step explanation:

8 years ago, ages of each family members is less by 8.

Let us assume that the current ages of the members are a, b, c, d, e, f, and g.

Average of current ages = $\frac{a+b+c+d+e+f+g}{7} = 23$

Ages of each member 8 years ago = a - 8, b - 8, c - 8, ..., g - 8.

Averages of ages 8 years ago = $\frac{a-8+b-8+c-8+d-8+e-8+f-8+g-8}{7}\\= [\frac{a+b+c+d+e+f+g}{7} ] - [\frac{8+8+8+8+8+8+8}{7} ]\\= [23] - [\frac{56}{7}]\\=23-8\\=15 \: years$