if three straws are chosen at random from a set of 9 straws whose lengths are 1cm, 2cm 3cm, 4cm, 5cm 6cm, 7cm, 8cm, and 9cm find the probability that the three straws will form a triangle.

Hans007
Feb 11, 2018

#1**+2 **

if three straws are chosen at random from a set of 9 straws whose lengths are 1cm, 2cm 3cm, 4cm, 5cm 6cm, 7cm, 8cm, and 9cm find the probability that the three straws will form a triangle.

There are 9C3 = 84 ways to chose 3 straws from the 9

They will from a triangle if the sum of the smallest 2 is greater than the length of the longer one.

So just count them. The trick is to dream up a good counting method.

Here is one I dreamed up. I hop I haven't made any silly errors. :)

**So the probability of being able to from a triangle is 33/84**

Melody
Feb 11, 2018