dv said:

The Rev Dodgson said:

From my Quoraing. It’s quite simple, but took me some time to work it out.

A commuter is in the habit of arriving at his suburban station each evening exactly at 5 o’ clock. His wife always meets the train and drives him home. One day he takes an earlier train, arriving at the station at four. The weather is pleasant, so instead of telephoning home he starts walking along the route always taken by his wife. They meet somewhere on the way. He gets into the car and they drive home, arriving at their house ten minutes earlier than usual. Assuming that the wife always drives at a constant speed, and that on this occasion she left just in time to meet the five o’ clock train, can you determine how long the husband walked before he was picked up?

Is it 55 minute?

Well 55 minutes works for me :).

I started of with algebra and too many unknowns, but eventually it occurred to me that:

The wife’s overall trip is reduced by 10 minutes.
She takes the same time in both directions, so the pick up is 5 minutes early.
He sets off 60 minutes early and is picked up 5 minutes early, so he walks for 55 minutes.