Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:
Number of defective bulbs |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
more than 6 |
Frequency |
400 |
180 |
48 |
41 |
18 |
8 |
3 |
2 |
One carton was selected at random. What is the probability that it has
(i) no defective bulb?
(ii) defective bulbs from 2 to 6?
(iii) defective bulbs less than 4?
Here, total events = total cartons =700
(i) no defective bulb
Favourable outcomes =400
(ii) defective bulbs from 2 to 6 = 2 or 3 or 4 or 5 or 6 defective bulbs
Favourable outcomes = 48 + 41 + 18 + 8 + 3 = 118
(iii) defective bulbs less than 4 = defective bulbs equal to 0 or 1 or 2 or 3
Favourable outcomes = 400 + 180 + 48 + 41 = 669
Probability is defined as
Here, total events = total cartons
(i) no defective bulb
Favourable outcomes
p (cartoon has no defective bulb) =
(ii) defective bulbs from 2 to 6 = 2 or 3 or 4 or 5 or 6 defective bulbs
Favourable outcomes
p(defective bulb from 2 to 6)
(iii) defective bulbs less than 4 = defective bulbs equal to 0 or 1 or 2 or 3
Favourable outcomes
p(defective bulbs less than 4)