All Exams Test series for 1 year @ ₹349 only
Question

Four cards are randomly selected from a pack of 52 cards. If the first two cards are kings, what is the probability that the third card is a king?

The correct answer is

2/50

This problem involves calculating a conditional probability, specifically the probability of drawing a third king from a standard deck of 52 cards, given that the first two cards drawn were kings. This scenario highlights the concept of dependent events, where the outcome of prior draws affects the possibilities for subsequent draws because cards are not replaced.

Cards Deck Composition

To solve this probability problem, it's crucial to understand the composition of a standard pack of 52 cards:

  • Total number of cards: 52
  • Number of suits: 4 (Hearts, Diamonds, Clubs, Spades)
  • Number of cards in each suit: 13 (Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King)
  • Number of King cards in a full deck: 4 (one King from each of the four suits)

Probability Scenario Breakdown

The question states that four cards are randomly selected. The key condition provided is that the first two of these selected cards are kings. We need to determine the probability that the third card drawn is also a king.

Initial State of the Deck

Before any cards are drawn, the deck is complete:

  • Total number of cards: 52
  • Number of King cards: 4

First Two Cards Drawn: Kings

Since the first two cards drawn are kings, these specific cards are removed from the deck. This is a process of sampling without replacement, meaning the deck changes after each draw.

  • After the first King is drawn, the deck now has \(52 - 1 = 51\) cards remaining. The number of King cards remaining is \(4 - 1 = 3\).
  • After the second King is drawn (from the deck of 51 cards), the deck further reduces to \(51 - 1 = 50\) cards. The number of King cards remaining is \(3 - 1 = 2\).

So, after the first two King cards have been drawn, the updated state of the deck for the next draw is:

  • Total number of cards remaining: 50
  • Number of King cards remaining: 2

Calculating Third Card Probability

Now, we need to calculate the probability that the third card drawn is a King, given the current state of the deck (50 total cards, 2 kings). The formula for probability is:

$$P(\text{Event}) = \frac{\text{Number of Favorable Outcomes}}{\text{Total Number of Possible Outcomes}}$$

For the third card to be a King:

  • Number of favorable outcomes (remaining kings): 2
  • Total number of possible outcomes (remaining cards): 50

Therefore, the probability that the third card is a King is:

$$P(\text{third card is a king}) = \frac{2}{50}$$

This calculation directly addresses the conditional probability based on the events that have already occurred.

Was this answer helpful?

Important Questions from Numerical Computation

  1. Ratio of the angles of a triangle are 1 : 2 : 6. What is the smallest angle?

  2. It would take one machine 4 hours to complete a production order and another machine 2 hour to complete the same order. If both machines work simultaneously at their respective constant rates, the time taken to complete the same order is ________ hours.

  3. Two design consultants, P and Q, started working from 8 AM for a client. The client budgeted a total of USD 3000 for the consultants. P stopped working when the hour hand moved by 210 degrees on the clock. Q stopped working when the hour hand moved by 240 degrees. P took two tea breaks of 15 minutes each during her shift, but took no lunch break. Q took only one lunch break for 20 minutes, but no tea breaks. The market rate for consultants is USD 200 per hour and breaks are not paid. After paying the consultants, the client shall have USD_remaining in the budget.

  4. What is the value of \(1 + \frac{1}{4} + \frac{1}{{16}} + \frac{1}{{64}} + \frac{1}{{256}} + \ldots ?\)

  5. A 1.5 m tall person is standing at a distance of 3 m from a lamp post. The light from the lamp at the top of the post casts her shadow. The length of the shadow is twice her height. What is the height of the lamp post in meters?

Need Expert Advice?

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App