A chalk box contains 5 pink chalks and 4 white chalks. If three items are picked at random, assuming that you return the chalk after picking each time, what is the probability that at least 1 of them is a pink chalk? *

91.22%

76.38%

19.83%

10.97%

Guest Apr 7, 2022

#1**+1 **

If you have no other way of approaching this problem, you can do it by listing all the possibilities:

PWW = (5/9)(4/9)(4/9) = ...

WPW = (4/9)(5/9)(4/9) = ...

WWP = (4/9)(4/9)(5/9) = ...

PPW = (5/9)(5/9)(4/9) = ...

PWP = (5/9)(4/9)(5/9) = ...

WPP = (4/9)(5/9)(5/9) = ...

PPP = (5/9)(5/9)(5/9) = ...

and adding all the results together.

This can also be done by using combinations but, if you forget the 'easy' way, don't give up!

geno3141 Apr 8, 2022