1. 20.
2. 4200.
Problems on
Average:
1. The average weight
of 10 persons increases by 3 kg when a new person comes in place of one of them
weighing 40 kg. What might be the weight of the new person?
Solution:
Increased sum = 3*10 = 30.
Weight of the new person = 40+30 = 70
kg.
(Note:
Since the average increases by 3kg, we’re adding 30 to 40)
2.The average weight
of 3 men A, B and C is 50 kg. Another man D joins the group and the average now
becomes 60 kg. If another man E, whose weight is 5 more than that of D,
replaces A, then the average weight of B, C, D and E becomes 58 kg. The weight
of A is:
Solution:
A+
B+ C = 50(3) = 150
A+
B+ C+ D = 60(4) = 240
B+
C+ D+ E = 58(4) = 232
E
= D+5
(A+
B+ C+ D)- (A+ B+ C) = D = 240-150 = 90.
E =
90+5 = 95.
(A+
B+ C+ D)-(B+ C+ D+ E) = A-E = 240-232 = 8.
A =
E+8 = 95+8 = 103.
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