Final answer:
The given machine is 40% efficient, as the efficiency is calculated by taking the ratio of the output energy (40 J) to the input energy (100 J), and then multiplying by 100 to convert to a percentage. By performing this calculation, a result of 40% is obtained, indicating a true statement.
Step-by-step explanation:
Efficiency can be calculated by taking the output energy or power of the machine and dividing it by the input energy or power and then multiplying by 100 to get the percentage. In this case, we're given an input energy of 100 J and an output energy of 40 J.
So, the efficiency of the machine in percentage can be calculated as:
(Output Energy/Input Energy) x 100%
Substituting the given values:
(40 J / 100 J) x 100%
Which simplifies to 40%, so the statement that the machine is 40% efficient is indeed true.
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