A jar contains exactly 6 balls : 5 red and 1 blue. if 5 balls are drawn from the jar at random all without replacement. what is probability they are all red?

Question

A jar contains exactly 6 balls : 5 red and 1 blue. if 5 balls are drawn from the jar at random all without replacement. what is probability they are all red?

Answer 1

Hi Leo, the probability is 1 / 6 the balls will be all red. The first ball drawn has a probability of being red of 5 /6.

 

The probability of the second ball being red is 4 / 5, since one ball has been removed from the total.

 

...

 

The probability of the fifth ball being red is 1 / 2, since there are only two balls left.

 

The probability of all balls being red is:

 

5 / 6 * 4 / 5 * 3 / 4 * 2 / 3 * 1 / 2 or 1 / 6

 

Questions?

Answer 2

For each case, it's the number of successes over the number of possibilities.  

 

(5/6)(4/5)(3/4)(2/3)(1/2)

 

=1/6.