Answer:
0.973
Explanation:
Solution
I'm going to discuss one way to do it, and then show a much better way.
If you attack the problem directly, there are 3 ways of placing just 1 day not being late
0.7 * 0.3 * 0.3 = .063
0.3 * 0.7 * 0.3 = .063
0.3 * 0.3 * 0.7 = 0.63
Making it on on time on two days gives you 3 equations as well
0.7* 0.7 * 0.3 = .147
0.7* 0.3 * 0.7 = .147
0.3 * 0.7 * 0.7 = .147
Making it on time all three days
0.7 * 0.7 * 0.7 = .343
If you add add these up, you should get 0.973
There is a better way. First calculate what happens if he is late all three days.
0.3 * 0.3 * 0.3 = 0.027 No on times (.7) anywhere.
If you take 0.027 away from 1, you get 0.973 That takes care of all the times he was on time. Much neater and easier, no?