Question

7. 10 years ago the average age of all 25 teachers of
the girls college was 45yrs. 4 years ago, the principal
has retired from her post at the age of 60 yrs. So
after one year a new principal whose age was 54
year recruited from outside. The present average
age of all the teachers is, if principal is also
considered as a teacher?
1) 54
2) 55
4) 49
5) 47
3) 49​

Answer 1

Answer:

54

Step-by-step explanation:

Total age of 25 teachers 10 years ago = 45 × 25 = 1125 years.

As one teacher was retired 4 years ago, total age of all teachers 4 years ago  = 1125 + 150 – 58 = 1217 years.

After one year, one more teacher was added with age 54 years, so the total age of all teachers 3 years ago = 1217 + 24 + 54 = 1295 years.

Now the present age of all teachers = 1295 + 75 = 1370 years. 

1370/25

Hence average age of all teachers =54.6