A box contains 10 bulbs,of which just three are defective. If a random sample of five bulbs is drawn, find the probability that the sample contains exactly one defective bulb.
A) 5/12 B) 7/12
C) 3/14 D) 1/12
A box contains 10 bulbs of which 3 are defective
Answer: A) 5/12
Total number of elementary events = 10C5
Number of ways of selecting exactly one defective bulb out of 3 and 4 non-defective out of 7 is 3C1*7C4
So,required probability =3C1*7C4/10C5 = 5/12.
Subject: Probability – Quantitative Aptitude – Arithmetic Ability