Question

A gasoline engine receives 200 J of energy from combustion and loses 150 J as heat to the exhaust. What is its efficiency? 75% 25% 33% 125%

Answer 1

25%.

Efficiency, in this case, means the work done...
Heat is a by-product of combustion and is lost energy. What remains the work done by the engine.

Our of 200 J, only 50 J are left out of 200 J.

So, 50 J remaining divided by 200 total I

50/200 = 1/4 = 25%

If you have any questions then please comment.

Answer 2

50/200×100%=25% is answer the formula is usefull energy output divided by total energy provided into 100%