8. A jar filled with 40 identical screws weighs 1.4 kg. The same jar when filled with 20 identical nails weighs 500 g. The mass of each screw is twice the mass of each nail. What is the mass of the empty jar?
J + 80 u -- > 1.4
J + 20 u -- > 0.5
60 u --> 1.4 - 0.5 = 0.9
20 u --> 20/60 x 0.9 = 0.3
J --> 0.5 - 0.3 = 0.2 kg
The mass of the empty jar is 0.2 kg.
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As appeared in PSLE 2010 exam:
ReplyDeleteA jar filled with 40 identical screws weighs 1.4 kg. The same jar when filled with 20 identical nails weighs 500 g. The mass of each screw is twice the mass of each nail.
What is the mass of the empty jar?