Question

closed.

Answer 1

6 are possible for the 1st flight and that leaves 5 for the second... multiply 6 by 5 to see how many different combinations of astronauts.

Answer 2

yep :)

Answer 3

Yes, that's how many possible combinations of astronauts there are.

Answer 4

Okay... so the first digit can be 2-9 which is 8 different possible numbers. For the second and third digits, 9 numbers are possible (for each). Since the fourth and final digit has to be even, it can be 2, 4, 6, or 8 (4 possibilities). To find your answer, multiply 8 by 9 by 9 by 4.

Answer 5

Correct.

Answer 6

I'm not sure about the first question, but the second one is wrong. If three teachers will be selected out of 20, 20 are possible for the first teacher. That leaves 19 for the second and 18 for the third. You would need to multiply 20 * 19 * 18 to find how many combinations are possible.

Answer 7

Oh okay I redid it now. Thanks for being so helpful! :)

Answer 8

No problem :) Let me know if you have any more questions.