The cylinders and pistons for the certain internal combustion engine are manufactured by process which provides a normal distribution of cylinder diameters with mean of 41.5 cm and standard deviation of 0.4 com.
Similarly, the distribution of piston diameters is normal with mean of 40.5 cm and standard deviation of 0.3 cm.
If the piston diameter is greater than cylinder diameter, the former can be reworked till the two "fit."
What proportion of cylinder-piston pairs will require to be reworked?