It was around the same for me: I knew I had to be careful for the first problem (that was accentuated by the fact that we were warned about the failure rate). For the second one though, I was too careful: I immediately started transcribing the problem in a pertinent format, i.e. I created the machine.minute unit (equivalent to the kWh unit) that allowed me to understand that a widget is made in 5 machine.minutes. Then I looked at the question, and computed that you’d need 500 machine.minutes to make 100 widgets, so 5 minutes with 100 machines. During that last step, something was bugging me, and it was the realization that the problem was much simpler and intuitive. I still finished what I was doing, then looked at it as a whole, and saw the "you need more widgets but have more machines so you need the same time" intuitively. And for the last one, it was very obvious of course.
It was around the same for me: I knew I had to be careful for the first problem (that was accentuated by the fact that we were warned about the failure rate). For the second one though, I was too careful: I immediately started transcribing the problem in a pertinent format, i.e. I created the machine.minute unit (equivalent to the kWh unit) that allowed me to understand that a widget is made in 5 machine.minutes. Then I looked at the question, and computed that you’d need 500 machine.minutes to make 100 widgets, so 5 minutes with 100 machines. During that last step, something was bugging me, and it was the realization that the problem was much simpler and intuitive. I still finished what I was doing, then looked at it as a whole, and saw the "you need more widgets but have more machines so you need the same time" intuitively.
And for the last one, it was very obvious of course.