Mathematics

Binomial distribution Questions

Chapter: Statistics and Probability | Total Available: 13 Real Questions

Question 1 of 10 Authentic UPSC NDA Question

Consider a random variable X which follows Binomial distribution with parameters n = 10 and p = 1/5. Then Y = 10 − X follows Binomial distribution with parameters n and p respectively given by

Step-by-Step Logic & Solution

Solution

Option (d) is correct.

Explanation:

A binomial random variable \( X \) follows the distribution with parameters \( n = 10 \) and \( p = \frac{1}{5} \).

The complementary variable \( Y = 10 - X \) counts the number of failures in \( 10 \) trials:

\[ Y \sim \text{Binomial}(n, p') \]

Where \( p' = 1 - p \):

\[ p' = 1 - \frac{1}{5} = \frac{4}{5} \]

Thus, \( Y \) follows a Binomial distribution with:

\[ Y \sim \text{Binomial}(10, \frac{4}{5}) \]

Final parameters for \( Y \) are \( n = 10 \) and \( p = \frac{4}{5} \).

📌 Hints / Properties Used:
  • Binomial Distribution: \( P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \)
  • Complementary probability: \( p' = 1 - p \)
📊 Visual Diagram Suggestion:

A diagram showing two binomial distributions for \( X \) and \( Y \) on a graph could illuminate how \( Y \) represents the distribution of failures while \( X \) represents successes.

📖 Factual Verification & Reference:

Verified against NCERT Class XII Mathematics, Chapter 13 (Probability).

Question 2 of 10 Authentic UPSC NDA Question

For a Binomial distribution with mean 6 and standard deviation √2, what is the value of P(X = 0)?

Step-by-Step Logic & Solution

Solution

Option (a) is correct.

Explanation:

Given a binomial distribution with mean \( \mu \) and standard deviation \( \sigma \): \[ \mu = n \cdot p = 6 \] \[ \sigma = \sqrt{n \cdot p \cdot (1 - p)} = \sqrt{2} \] Squaring the standard deviation: \[ n \cdot p \cdot (1 - p) = 2 \] We have two equations: \[ 1. n \cdot p = 6 \quad (1) \] \[ 2. n \cdot p \cdot (1 - p) = 2 \quad (2) \] From equation (1), we can express \( n \): \[ n = \frac{6}{p} \] Substituting into equation (2): \[ \frac{6}{p} \cdot p \cdot \left( 1 - p \right) = 2 \] \[ 6(1 - p) = 2 \] \[ 6 - 6p = 2 \] \[ 6p = 4 \\ p = \frac{2}{3} \] Now substituting \( p \) back to find \( n \): \[ n = \frac{6}{\frac{2}{3}} = 9 \] Thus, \( n = 9 \) and \( p = \frac{2}{3} \). Now calculating \( P(X = 0) \): \[ P(X = 0) = (1 - p)^n = \left( \frac{1}{3} \right)^9 \] \[ = \frac{1}{19683} \] In conclusion: \[ P(X = 0) = \left( \frac{1}{3} \right)^9 \quad (Final) \]
📌 Hints / Properties Used:
  • Binomial Mean: \( \mu = n \cdot p \)
  • Binomial Variance: \( \sigma^2 = n \cdot p \cdot (1 - p) \)
  • Probability for Binomial Distribution: \( P(X = k) = \binom{n}{k} p^k (1 - p)^{n-k} \)
📊 Visual Diagram Suggestion:

A flowchart depicting how to compute the mean and standard deviation for a binomial distribution, along with probability calculations would aid understanding.

📖 Factual Verification & Reference:

Verified against NCERT Class XII Mathematics, Chapter on Probability.

Question 3 of 10 Authentic UPSC NDA Question

Let X be a random variable following binomial distribution with parameters n = 5 and p = k. Further, P(X = 1)= 0.4096 and P(X = 2) = 0.2048. What is the value of k?

Step-by-Step Logic & Solution

Question 4 of 10 Authentic UPSC NDA Question

Under which of the following conditions may binomial distribution be used?

 I. The number of trials is infinite and not fixed.

II. The trials are independent. III. Each trial has two possible outcomes.

Select the correct answer using the code given below.

Step-by-Step Logic & Solution
Explanation: In binomial distribution number
trial is finite and fixed and independent. Each
trial has two possible outcomes (success and
failure).
So, statement II and III are correct.
Question 5 of 10 Authentic UPSC NDA Question

Direction for Questions (97-98): Consider the following for the two (02) items that follow: Let X be a random variable following binomial distribution with parameters n = 6 and p = k. Further, 9P(X = 4) = P(X = 2).

 What is the value of P(X = 3)?

Step-by-Step Logic & Solution

Question 6 of 10 Authentic UPSC NDA Question

Direction for Questions (97-98): Consider the following for the two (02) items that follow: Let X be a random variable following binomial distribution with parameters n = 6 and p = k. Further, 9P(X = 4) = P(X = 2).

What is the value of k?

Step-by-Step Logic & Solution

Question 7 of 10 Authentic UPSC NDA Question

Let X be a random variable following binomial distribution whose mean and variance are 200 and 160, respectively. What is the value of the number of trials (n)?

Step-by-Step Logic & Solution

Question 8 of 10 Authentic UPSC NDA Question

In a binomial distribution, if the mean is 6 and the standard deviation is √2, then what are the values of the parameters n and p, respectively?

Step-by-Step Logic & Solution

Question 9 of 10 Authentic UPSC NDA Question

If a random variable (x) follows binomial distribution with mean 5 and variance 4 and 523P(X = 3) = λ4λ, then what is the value of λ?

Step-by-Step Logic & Solution

Question 10 of 10 Authentic UPSC NDA Question

In a Binomial distribution B(n, p), n = 6 and 9P(X =4) = P(X = 2). What is p equal to ?

Step-by-Step Logic & Solution

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