Question

A bag contains 5 white 7 red and 8 black balls if 4 balls are drawn one by one without replacement find the probability that all are white

Answer 1

Answer:

1 / 969

Step-by-step explanation:

P(all 4 are white)

= ( # ways of drawing 4 white balls from 5 ) / ( # ways of drawing 4 balls from 5+7+8=20 balls )

= $\displaystyle\frac{\dbinom54}{\dbinom{20}4}$

= $\displaystyle\frac{5\times4\times3\times2}{20\times19\times18\times17}$

= $\displaystyle\frac{1}{19\times3\times17}$

= 1 / 969