Book Online Demo

Check Your IQ

Try Test

Courses

A bag contains white, black, and red balls only. A ball is drawn at random from the bag. The probability of getting a white ball is $310$ and that of a black ball is $25$ . Find the probability of getting a red ball. If the bag contains 20 black balls, then find the total number of balls in the bag.

see full answer

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

Probability =

410

, Total balls = 11

Probability =

110

, Total balls = 40

Probability =

210

, Total balls = 45

Probability =

310

, Total balls = 50

answer is D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

It is given that a bag contains white, black, and red balls only.
The probability of white ball is

310 .

The probability of black ball is

25

.
We know that, the sum of the different probability in a particular observation is always equal to 1.

P (B) + P (W) + P (R) = 1 ⇒ P (R) + 310 + 25 = 1 ⇒ P (R) = 1 − 310 − 25 ⇒ P (R) = 310

Hence, the probability of getting a red ball is

310 .

Number of black balls in the bag = 20.
Probability of getting black ball,

P (B) = n (B) n (T)

.
Where n(B)(Number of black balls) = 20 and n(T) = total number of balls.
Thus,

n (T) = n (B) P (B)

⇒ n (T) = 2025 ⇒ n (T) = 2052 ⇒ n T = 50

Hence, the probability of getting red balls is

310

and the total balls in the bag is 50.
Therefore, the correct answer is option (4).

Watch 3-min video & get full concept clarity