(1) 3 * 15 (km) /60 (km) * 60 (min) =45 minutes > 42f minutes.

According to the meaning of the question, at the fault, four people were left for another car to pick up, so the good car had to go to the county seat first, then come back to break down, and then send the other four people to the county seat, so it took 45 minutes to walk three times 15km, which was not good.

(2) Scheme: After the fault occurs, the four people left behind will walk and wait for another car to come back to pick them up.

Note: The sum of the walking distances of a small person and another car to the county town and back when they meet four people is 15(km)*2=30km, and the speed ratio between the car and people is 60: 5 = 12: 1, so the distance of people is 13 of 30km. The distance traveled by people is 30/ 13km. So the total time is

45-(30/ 13)*2/60=0.673 hours =40.4 minutes

( 1) 1 (+3) → 4 (× 2) → 8 (+3) → 1 1 (× 2) → 22

(2) This number is a big even number, so you can get it by adding a lot from 2 to 4.