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Question
The arms of a beam balance are 20 cm and 21 cm, but the pans are of equal weight. By the method of double weighing the weights are found to be 1000 g and 20 g. Find the actual weight of the body
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Solution

m = mass of each pan
m0 = actual mass of the body
(100 + m)20 = (m + m0) 21

Dividing the two equations
`21/20 = ((100 + "m")20)/((20 + "m") 21)`
1.1 (20 + m) = (1000 + m)
22 + 1.1m = 1000 + m
0.1m = 978
m = 9780g
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