One more puzzle!

A person goes to his house from office in car. Car with driver starts from his house at 7p.m. and reaches office and picks him up and drops him at his home. One day, he is done with his work at 5.30p.m. and starts walking to his home instead of waiting for car. He finds the car on his way and goes to his house. He reaches his house 20 minutes eariler than his usual time. At what time, he usually reaches his home?

Some Puzzles

- Producer Consumer Problem:
Scenario 1: Traditional Problem
Scenario 2: Producer should produce and puts in the shared buffer. Every consumer should consume the item before we delete it from the shared buffer.

- In race court, there are 5 tracks and 25 horses to race. We need to find the top 3 from the 25 horses. Assumption is - Horses perform in the same way during all the races and we can't record the times. You can make horses to participate any number of times. In how many races, you can find the top 3?