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:

No. 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 more than 1 defective bulbs?

• A. $\frac{60}{350}$
• B. $\frac{67}{350}$
• C. $\frac{71}{350}$
• D. $\frac{77}{350}$

Answer 1

The correct option is A $\frac{60}{350}$

To find the number of cartons with no. of defective bulbs from 2 to 6, we can remove the number of cartons with no. of defective bulbs 0 or 1 from the whole set

No. of cartoons with 0 or 1 defective bulb $=400+180=580$

So, $P\text{(carton with 2 to 6 defective bulbs)}$

$=1-P\text{(cartoon with 0 or 1 defective bulb)}$

$=1-\frac{580}{700}$

$=\frac{120}{700}$

$=\frac{60}{350}$