A fair coin is tossed times. Let denote the number of heads obtained. What are the mean () and variance () of the random variable ?
Answer and explanation
Correct answer: B. and
- Step 1: follows a binomial distribution with parameters and ().
- Step 2: Mean is .
- Step 3: Variance is .
Answer
and .
Why not the others: forgets to multiply by ; divides the mean by 2; and assumes 100% success rate.
Practise more Vectors, 3D Geometry and Probability.
Free questions with an explanation for every one, and full timed CBSE Class 12 mock tests.
More Vectors, 3D Geometry and Probability questions
- If are the direction cosines of a straight line in three-dimensional space, what is the value of ?
- Which formula gives the shortest distance between two skew lines and…
- If , , and , what is the value of ?
- Two events and with non-zero probabilities are statistically independent if and only if which equality holds?
- Bag I contains 3 red and 4 black balls, while Bag II contains 5 red and 6 black balls. One bag is chosen at random with equal probability an…
- In a linear programming problem, if the feasible region is bounded, where does the optimal (maximum or minimum) value of the objective funct…