17. The ratio of the number of girls to that of
boys in a class 2:3. If the average weight of
the boys in the class is 40 kg and that of the
class is 38kg, find the average weight of
the girls.
Answers
Let x be the number of boys, then the number of girls will be (60−x).
The mean weight of boys is 50 kg, then the total weight of boys will be, 50x.
The mean weight of girls is 30 kg, then the total weight of girls will be 30(60−x)=1800−30x.
The mean weight of 60 students is 40 kg, so
totalno.ofstudents
weightofgirls+weightofboys
=40
60
1800−30x+50x
=40
x=
20
600
x=30
So, the number of boys is 30 and the number of girls is (60−30)=30.
Answer:
Concept:
Average is the arithmetic mean, which is derived by multiplying a collection of integers by the count of those numbers.
Step-by-step explanation:
Given:
The ratio of the number of girls to boys = 2 : 3
The average weight of boys = 40kg
The average weight of total class = 38kg
Find:
The average weight of girls
Solution:
By using the given information
Boys : Girls = 3 : 2
The average weight of boys : average weight of girls = x kg : 40kg
= 40kg - 38kg = 2kg
= 38kg - xkg
The ratio will be 2 / 38-x = 3/2
by solving, we will get x = 35
Hence, the average weight of the girls is 35kg.
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