A bag contains some red and some white balls. A ball is drawn at random from the bag. If the probability of getting a red ball is 2/7 then the probability of getting a white ball is

A bag contains some red and some white balls. A ball is drawn at random from the bag. If the probability of getting a red ball is 2/7 then the probability of getting a white ball is
(A) 1/14
(B) 5/7
(C) 1/7
(D) 2/7

Solution : Correct answer is : (B) 5/7

Probability of getting a red ball = $\frac{2}{7}$

The total probability of all possible outcomes = 1

There are only two possible outcomes:

• Getting a red ball
• Getting a white ball

So,$$P(\text{Red}) + P(\text{White}) = 1$$

Substitute the given value:$$\frac{2}{7} + P(\text{White}) = 1$$

Now solve for $P(\text{White})$

P(White): 1 – 2/7

Convert 1 into fraction form:$$1 = \frac{7}{7}$$

So,

P(White) = 7/7​−7/2​

= 5/7

Correct answer is : Option (B) 5/7