Question

EXAMPLE 1 The average weight of a class of 40 students is 30 and
the average weight of a class of 20 students is 15. Find the average
weight of both the combined classes :
(a) 20
(b) 25
(c) 17.5 (d) 15​

Answer 1

Answer:

$= > \frac{sum \: of \: average \: weight \: of \: two \: classes}{total \: no. \: of \: student} = \frac{30(40) + 15(20)}{40 + 20} = \frac{1200 + 300}{60} = \frac{1500}{60} = \frac{50}{3} = 16.67$

Hope this answer helps you ^_^ !

Answer 2

ANSWER:The ans is b) 25

AVERAGE = (sum of average weight of two classes) / total no. of students

=[ 40(30) + 20(15) ] / 40 + 20

=( 1200 + 300 ) / 60

= 1500 / 60

= 150 / 6

= 25.

(The mistake above was in dividing)

HOPE THIS WILL HELP.