Home
MCQ QUIZ APP DOWNLOAD

What is the correct answer?

4

A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that at least one of these is defective is

A. 719

B. 619

C. 519

D. 419

Correct Answer :

A. 719



Please remember that Maximum portability is 1.
So we can get total probability of non defective bulbs and subtract it form 1 to get total probability of defective bulbs.
So here we go,
Total cases of non defective bulbs
c216=16×152×1=120
Total cases =c220=20×192×1=190
probability = 120190=1219
P of at least one defective = 11219=719