lets find the wieght..!!

Probability Level 1

The average weight of a group of 150 students in a class is 60 kg. If the mean of weights of all the 50 male students in the class is 70 kg, then the average weight of 100 girls in the class is:

85 60 55 40

Sunitha P by sunitha p , 28, India

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3 solutions

Tasnim Rawat
Mar 13, 2014

We have average of 150 students = 60 kg.

Average of 50 male = 70 kg , Find average of 100 female = x = ?

(Avg of 50 + Avg of 50 + Avg of 50 ) / 3 = Avg of 150

(70 + x + x) /3 = 60

70 + 2 x = 180

x = 55 Kg

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Yogesh Waran
Mar 12, 2014

total weight be x and weight of boys be y x/150=60 Then x=9000 y/50=70 Then y=3500 x-y=5500 5500/100=55 so the average of girls weight is 55

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Shreyas Shastry
Mar 7, 2014

150 students mean weight is 60

so mean =sum of students/150=60

so by cross multiplication we get sum of weights of total students as 9000kg

now do the same calculations for male students it comes to 3500kg

now subtract total weight with male students weight=9000-3500

we get 5500 this is the sum of weights of remaining students who are girls

so to find there mean = 5500/100

we get 55

0 Helpful 0 Interesting 0 Brilliant 0 Confused

Total weight = 150 × 60 = 9000 kg Total male students weight = 50 × 70 = 3500 kg Rest weight = 9000 – 3500 = 5500 kg Then girls average weight is = 5500/100 = 55 kg

sunitha p - 7 years, 1 month ago

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