Question

(a) The mean of the masses of a group of four student is 30 kg.
One student joins the group .The mean of the masses of the five students is 32 kg.
Find the mass of the student who joined the group.


(b)The mean of the five articles is 215 g. When another article is added, the mean of the masses of the six articles is 220 g. Find the mass of the sixth article.

Answer 1

Answer:

Given

mean weight per student in a group of 7 students if 55kg

Mean weight of 7 students=55kg

No. of students=7

∴ Mean=

No. of observations

sum of observations

=

7

sum of weights of 7 students

55×7= sum of weights of 7 students

Sum of weights of 7 students=385kg

and given individual weights of 6 of them(in kg) are

52,54,53,55,56 & 54

Total weights of 6 students

=52+54+55+53+56+54

=324 kg

∴ The weight of the seventh student

=Total wieghts of 7 students− total weights of 6 students

=385−324

=61 kg.