Listen NCERT Audio Books - Kitabein Ab Bolengi
An experiment succeeds twice as often as it fails. Find the probability that in the next six trials, there will be at least 4 successes.
It is given in the question that,
Probability of failure = x
And, probability of success = 2x
∴ x + 2x = 1
3x = 1
∴
Let us now assume
Also, X be the random variable that represents the number of trials
Hence, by binomial distribution we have:
∴ Probability of having at least 4 successes
= P (X = 4) + P (X = 5) + P (X = 6)
Suppose we have four boxes A, B, C and D containing coloured marbles as given below:
Box | Marble colour | ||
Red | White | Black | |
A | 1 | 6 | 3 |
B | 6 | 2 | 2 |
C | 8 | 1 | 1 |
D | 0 | 6 | 4 |
One of the boxes has been selected at random and a single marble is drawn from it. If the marble is red, what is the probability that it was drawn from box A?, box B?, box C?