Target Exam

CUET

Subject

Maths. Section B1

Chapter

Probability

Question:

Four cards are successively drawn without replacement from a deck of 52 playing cards. What is the probability that all the four cards are king?

Options:

$\frac{1}{270725}$

$\frac{1}{13^4}$

$\frac{4}{52^4}$

$\frac{1}{52!}$

Correct Answer:

$\frac{1}{270725}$

Explanation:

The correct answer is Option (1) → $\frac{1}{270725}$ ##

Let $E_1, E_2, E_3$ and $E_4$ are the events that the first, second, third and fourth card is king, respectively.

$∴P(E_1 \cap E_2 \cap E_3 \cap E_4) = P(E_1) \cdot P(E_2 | E_1) \cdot P(E_3 | E_1 \cap E_2) \cdot P[E_4 | (E_1 \cap E_2 \cap E_3)]$

$= \frac{4}{52} \cdot \frac{3}{51} \cdot \frac{2}{50} \cdot \frac{1}{49} = \frac{24}{52 \cdot 51 \cdot 50 \cdot 49}$

$= \frac{1}{13 \cdot 17 \cdot 25 \cdot 49} = \frac{1}{270725}$