Drawing/Picking/Choosing a red or black ball from a bag/urn/box
Problem 3
A bag contains 3 red balls, 4 white balls and 7 black balls the probability of drawing a red or a black ball is
Ans :
| 5 |
| 7 |
Solution
Total number of balls in the bag
= 3 Red + 4 White + 7 Black
= 14
Experiment :
Drawing a ball at random from the bag containing 3 red, 4 white and 7 black balls
Total Number of Possible Choices
= Number of ways in which one ball can be drawn from the total 14
| ⇒ n | = | 14C1 | ||
| = |
| |||
| = | 14 |
Let
A : the event of drawing a red or a black ball
For Event A
| Favorable (Red + Black) | Unfavorable (Others) | Total | |
|---|---|---|---|
| Available | 10 | 4 | 14 |
| To Choose | 1 | 0 | 1 |
| Choices | 10C1 | 4C0 | 14C1 |
Number of Favorable Choices
= Number of ways in which one red or black ball can be drawn from the total 10
| ⇒ mA | = | 10C1 | ||
| = |
| |||
| = | 10 |
Probability of the ball drawn being red or black
⇒ Probability of occurrence of Event A
| = |
|
| ⇒ P(A) | = |
| ||
| = |
| |||
| = |
|
Author : The Edifier