You have 9 pieces of wood of different lengths that you are attempting to glue together that will h?

Question

You have 9 pieces of wood of different lengths that you are attempting to glue together that will have a length of exactly 10 inches. The straw lengths are 1 inch, 2 inches, 3 inches, 4 inches, 5 inches, 6 inches, 7 inches, 8 inches, and 9 inches. What is the probability that you randomly choose one piece of wood keep it then randomly choose the second one to give you a total length of 10 inches.

(*Hint* Make a list of the combinations that will add up to 10.)


Part 1: 
Express the probability of the 1st chosen piece of wood.
Express the probability of the 2nd chosen piece of wood.

Answer

This is awfully simple. You have nine choices and eight of them are valid, so the odds of the first piece are 8/9. There is only one valid choice for the second, so the odds are 1/8. The odds of both choices being valid are 8/9 x 1/8 = 1/9.

You have 9 pieces of wood of different lengths that you are attempting to glue together that will h?

Answers (1)