+0

if three straws are chosen at random from a set of 9 straws

-1
1007
3
+110

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.

Feb 11, 2018

#1
+111600
+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

Feb 11, 2018
#2
+112375
+1

I like that "table" trick, Melody.....that makes the counting way easier !!!

Feb 11, 2018
#3
+111600
+1

Thanks Chris, it did work rather well - I thought so too

Melody  Feb 11, 2018