A train has 10 cars numbered 1 through 10. If the cars are coupled randomly, what is the probability that the first 3 cars are in car number order?

1/720

2/15

1/5,040

If they are in order the highest number for the first car is 7 ... and the other cars can only have one specific value because of the first, so

(7/10) (1/9) (1/8) = 7/720

Okay, I see that they mean the order has to be 1,2,3 instead of all ordered sets like 7,8,9 and 4,5,6 for example ...

So if they have to be 1,2,3 then

(1/10) (1/9) (1/8) = 1/720