Question

A bag contains 4 white, 7 black and 5 green balls. What is the probability of picking white?

Answer 1

Hint: In this question it is given that a bag contains 4 white, 7 black and 5 green balls. So to find the probability of picking one white ball, you have to know that Probability = $\dfrac{Number\ of\ favourable\ outcomes}{Total\ number\ of\ outcomes}$, where, number of favourable outcomes is the number of ways that an event can happen.

Complete step-by-step answer:
So the event for this question is ‘Picking one white ball’, and we have given,
No. of white balls = 4,
No. of black balls = 7,
No. of green balls = 5,
Total number of balls = 4+7+5 = 16.
So now if we try to pick one ball from 16 balls, then we can pick 16 different ways or we can say that the total possible outcomes is 16, i.e Total possible outcomes = 16.

And since we have given 4 white balls so we can pick one white ball from 4 white balls in 4 different ways, which is our favourable outcome for this event, i.e Number of favourable outcomes = 4.

So, Probability of picking white ball = $\dfrac{Number\ of\ favourable\ outcomes}{Total\ number\ of\ outcomes}$
= $\dfrac{4}{16}$ = $\dfrac{1}{4}$
It is our required solution.

Note: To solve this type of question, firstly you have to know the probability formula and also you have to identify what is the event, by this you can easily find the number of ways for an event.