Question

118 The average age of a class of 35 students is 15 years. If the teachers age is also
included the average age increases by one year. Furthermore, if the average age
of the teacher's family having a wife and a son is 40 years and the sons' age is
80% less than his mother's age, then the age of the teacher's wife is :
(a) 47.5 years
(b) 55.5 years (©) 57.5 years (d) 50 years
(SSC, 10+2, 10.11.2013)​

Answer 1

Answer:

let wife's age =x

15+36*1=51

Teacher+wife+son=120

51+x +20/100x=120

120x/100=69

x=57.5