A Carnot's engine is made to work between `200^(@)C` and `0^(@)C` first and then between `0^(@)C` and `-200^(@)C`. The ratio of efficiencies of the engine in the two cases is

Explanation

`eta = ((T_(1) -T_(2)))/(T_(1))`
`eta _(1) = ((473-273))/(473)=(200)/(473)`
` eta _(2) =(273 -73))/(273) =(200)/(273)`
` (eta _(1))/(eta_(2))= (273)/(473) = 0.577`