Question

Hi i am Grace and i realllyyyyyy need help on this. If you could please help that would be great.

Answer 1

The probability of picking a black ball first is $\dfrac{4}{5}$, because there are 4 black balls and 1 white ball which is 5 balls in total. After picking the first ball, 4 balls remain - 3 black and 1 white, so the probability of picking a white ball is $\dfrac{1}{4}$.
So, the probability of picking a black ball first followed by a white ball is $\dfrac{4}{5}\cdot\dfrac{1}{4}=\dfrac{1}{5}$