Question

A flashlight has 10 batteries out of which 4 are dead. If 3 batteries are selected without replacement and tested, then the probability that all 3 are dead is

• A. $\frac{1}{30}$
• B. $\frac{2}{8}$
• C. $\frac{1}{15}$
• D. $\frac{1}{10}$

Answer 1

The correct option is A $\frac{1}{30}$

By multiplication rule of probability,
Probability that all 3 batteries are dead $=\frac{4}{10}\times \frac{3}{9}\times \frac{2}{8}=\frac{1}{30}$