Question

1. The arithmetic mean age of the first group of 80 students is
10 years and that of second group of 20 students is 15 years.
Find the arithmetic mean age of all the students.​

Answer 1

Answer:

$15years$

Step-by-step explanation:

Mean of 1st 80 students = 15 years

Total age =80×15years

=1200years

Mean of 2nd 20 students= 15 years

Total age of 20 students. = 20 ×15years

= 300years

Total number of students =80+20

=100

Total age of 100 students =(1200+300 )years

=1500 years

Mean age of 100 students= 1500years/100

=15 years