Every day Sunita starts from her home in her car, picks up her son from the bus stop and travels back home. One day her son reached the bus stop 1 hour early and he started walking towards home. Sunita started from her home at the usual time and picked up her son midway and returned home 20 minutes earlier as compared to the usual time. Find the ratio of the speed of Sunita’s car to the speed of her son.
The above question is from CC50. My doubt is, it is mentioned that the son reached bus stop 1 hour early, Let's say generally his mom take him up from bus stop at 12 pm. But that day he reached at 1 hour before and started walking towards home, i.e. the son reached stop at 11 am. Now before his mom starts at 12pm, he must walked for 60 mins, then how come the son walked only for 50 mins as given in the solution?