CAT Exam  >  CAT Questions  >  A certain biased coin when tossed has a proba... Start Learning for Free
A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?
  • a)
    5/16
  • b)
    1/32
  • c)
    40/243
  • d)
    80/243
  • e)
    None of the above
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
A certain biased coin when tossed has a probability p of showing head....
The probability that the coin will show tail = 1 - p. Let us first find the probability of getting exactly one head in 5 tosses.
Let only the first toss show head.
Probability o f this event = p x (1 - p)4 But second, third, fourth or fifth tosses can also show heads.
Hence, probability that there is exactly one head in 5 tosses = 5 x p x (1 - p)4
Similarly, let’s find the probability of getting exactly two heads in 5 tosses.
Let only the first and second tosses show head.
Probability = p2 * (1 - p)3 Now, there are 5C2 different ways in which we get exactly 2 heads in 5 tosses. 
Hence, probability that there are exactly 2 heads in 5 tosses = 5C2 x p2 x (1 - p)3 Hence, 5 x p x (1 - p)4 = 5C2 x p2 x (1 -p) 3
1 - p = 2p. 
p = 1/3
Now, let’s find the probability that there are exactly 3 heads in 5 tosses.
Let only first three tosses show head.
Hence, probability = p3 * (1 - p)2 But there are 5C3 different ways in which we can get exactly 3 head in 5 tosses.
Hence, probability of getting exactly 3 heads in 5 tosses = 5C3 x p3 x (1 - p)2
= 40/243
Hence, option 3.
View all questions of this test
Most Upvoted Answer
A certain biased coin when tossed has a probability p of showing head....
Let's assume that the probability of getting a head on a biased coin is p. Therefore, the probability of getting a tail would be 1-p.

To find the probability of getting exactly one head in 5 tosses, we need to consider the different ways this can happen:

- H T T T T
- T H T T T
- T T H T T
- T T T H T
- T T T T H

The probability of each of these outcomes occurring is p * (1-p) * (1-p) * (1-p) * (1-p), which is equal to p * (1-p)^4.

Similarly, to find the probability of getting exactly two heads in 5 tosses, we need to consider the different ways this can happen:

- H H T T T
- H T H T T
- H T T H T
- H T T T H
- T H H T T
- T H T H T
- T H T T H
- T T H H T
- T T H T H
- T T T H H

The probability of each of these outcomes occurring is p^2 * (1-p) * (1-p) * (1-p), which is equal to p^2 * (1-p)^3.

According to the given information, the probability of getting exactly one head should be equal to the probability of getting exactly two heads:

p * (1-p)^4 = p^2 * (1-p)^3

We can simplify this equation by dividing both sides by p * (1-p)^3:

(1-p) = p

Simplifying further, we get:

1 = 2p

Therefore, p = 1/2.

Now, to find the probability of getting exactly three heads in 5 tosses, we need to consider the different ways this can happen:

- H H H T T
- H H T H T
- H H T T H
- H T H H T
- H T H T H
- H T T H H
- T H H H T
- T H H T H
- T H T H H
- T T H H H

The probability of each of these outcomes occurring is (1/2)^3 * (1/2) * (1/2), which is equal to 1/8 * 1/2 * 1/2, which simplifies to 1/32.

Therefore, the probability of getting exactly three heads in 5 tosses is 1/32, which is option (b).
Attention CAT Students!
To make sure you are not studying endlessly, EduRev has designed CAT study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in CAT.
Explore Courses for CAT exam

Similar CAT Doubts

A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer?
Question Description
A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? for CAT 2024 is part of CAT preparation. The Question and answers have been prepared according to the CAT exam syllabus. Information about A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for CAT 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer?.
Solutions for A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for CAT. Download more important topics, notes, lectures and mock test series for CAT Exam by signing up for free.
Here you can find the meaning of A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer?, a detailed solution for A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? has been provided alongside types of A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A certain biased coin when tossed has a probability p of showing head. If the probability that there will be exactly one head in 5 tosses is same as the probability that there will be exactly two heads in 5 tosses, then what is the probability that there will be exactly 3 heads in 5 tosses?a)5/16b)1/32c)40/243d)80/243e)None of the aboveCorrect answer is option 'C'. Can you explain this answer? tests, examples and also practice CAT tests.
Explore Courses for CAT exam

Top Courses for CAT

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev