The average weight of a group of boys is 48 kg. If 8 boys of average weight 51 kg leave and 3 boys o

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18 Jul 2022 Average

The average weight of a group of boys is 48 kg. If 8 boys of average weight 51 kg leave and 3 boys of average weight 42 kg join the group, then the average weight of group decreases by 1 kg 50 gm. Find the initial number of boys in a group

OPtion

1) 38
2) 48
3) 42
4) 39
5) 45
6) 33
7) 49
8) 54
9) 40
10) None of these

Solution

Let there are 'n' boys in a group initially, then their total weight=48n
When, 8 boys of average weight 51 kg leave and 3 boys of average weight 42 kg join the group, then of boys left = n-8+3 = n-5
New average of a group = (48n - 8*51 + 3*42) / (n-5) = (48 - 1.05)
48n - 408 + 126 = 46.95n - 234.75
1.05n = 47.25
n = 45
Correct Option 5)

Correct Option: 5 Best Solution (1)

G.S.Kantharao   2 years AGO

Let the boys be X
Average of X=48
Change=-8*51+3*42=-282
Average of X-5=46.95
48X+46.95X-234.75=282
1.05X=47.25=>X=45
My option is 5👈

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