Question

The average weight of 3 people is 40 kg. The average weight of first and second is 35 kg and the
average weight of second and third is 30 kg. What is the age of third one is?

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Answer 1

Answer:

A+B+C/3 = 40 kg

A+B+C = 40×30 =120..(1)

A+B/2 = 35

A+B =35×2=70..(2)

A+C/2= 30

B+C =30×2=60..(3)

A+B+B+C= 70+60= 130

from eq. 1

A+B+C = 40×30 =120..(1)

A+B+B+C= 70+60= 130

A+B+C+B+ = 130..

120 + B = 130

B = 10

..

A= 70-10 = 60

C= 60-10 = 59

B= 70-60 = 10