Q. There are 5 duplicate and 10 original items in an automobile shop and 3 items are brought at random by a customer. The probability that none of the items is duplicate, is
A) 20/91
B) 22/91
C) 24/91
D) 89/91
Explanation
(c)
Duplicate =5, original = 10
Taking 3 times.
The probability that none of the items is duplicate $ie$, all the three are original
$= \frac{{\ ^{10}C}_{3}}{{\ ^{15}C}_{3}} = \frac{24}{91}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.