Recent content by Michael Si

There are n objects, within which there are p identical objects. Now, suppose if you randomly choose r objects from the n objects. How many permutations will you get from the r objects you choose?

Thank you. :smile: Well, you're right. Since the conditions aren't clearly stated, factors like air-resistance can be ignored so as to simplify the problem. And indeed, the rock would not necessarily return. But I am not sure where the rock would be if i doesn't fall back. :rolleyes: If it...

A rock is launched vertically. During the last second of the flight, the rock covers one-half of the entire distance covered during the flight. What is the maximum possible duration of the flight? (Hint: answer is not 2 seconds.) I've tried to use integration to solve an equation of motion...