Question

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 defective bulbs less than 4?

Answer 1

Total number of cartons, n(S) = 700

Number of cartons which has defective less than 4,

n(E₃) =  400 + 180 + 48 + 41 = 669

∴ The probability that the defective bulbs less than  4 = `(n(E_3))/(n(S)) = 669/700`

Hence, the probability that the defective bulbs less than 4 is `669/700.`