Friday
April 18, 2014

Homework Help: maths

Posted by Candice on Thursday, October 11, 2012 at 9:38am.

A box contains 20 balls, of which 5 are red, 5 are blue, 5 are white and 5 are green. Suppose a sample of 5 balls are chosen without replacement.

a) find the probability that the sample contains balls of all the same colour

(answer is 4/ 20C5, but why isnt it 5/20C5??)

b) find the probability that the sample contains three balls of one colour and two balls of another colour.

The teacher wrote

5C3 x 5C2 x 4P2
---------------
20C5

Could you please explain why this is?
Thanks!!

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

maths-probabilty - A box contains 5 red balls and 6 black balls. in how many ...
maths-probabilty(urgently needed) - A box contains 5 red balls and 6 black balls...
math - a box filled with identically shaped balls contains 5 balls with the ...
statistics - A box contains 3 white and 5 black balls. Four balls are drawn at ...
Probability again - A box contains 6 red balls, 4 blue balls, and 2 green balls...
math - A box containing 5 red balls and 3 green balls weighs 43 g. When the box ...
science - A box contains 10 balls of which 6 are red (R) and 4 are white (W) . ...
math - A box contains 8 blue balls and 2 red balls. Three balls are selected ...
Statistics - Box A contains 4 red and 6 blue balls. Box B contains 5 red and 10...
statistics - Box A contains 4 red and 6 blue balls. Box B contains 5 red and 10 ...

Search
Members