If three dice are thrown, then the probability that they show the numb...
A.P. with common diff one are =4=(123)(234)(345)(456)
A.P. with common diff 2 are =2=(135)(246)
A.P. with common diff 0 are =6
⇒P=2+4+6/216=1/18
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If three dice are thrown, then the probability that they show the numb...
Let's consider the numbers on the three dice as a, a + d, and a + 2d, where a is the first term and d is the common difference. We need to find the probability that these three numbers are in arithmetic progression (A.P.).
There are a total of 6^3 = 216 possible outcomes when three dice are thrown since each die has 6 possible outcomes.
To find the favorable outcomes, we need to consider the possible values of a and d that satisfy the condition of an A.P.
- Finding the possible values of a and d:
For a = 1, the possible values of d can be 1, 2, 3, 4, or 5.
For a = 2, the possible values of d can be 1, 2, 3, or 4.
For a = 3, the possible values of d can be 1, 2, or 3.
For a = 4, the possible values of d can be 1 or 2.
For a = 5, the only possible value of d is 1.
Therefore, there are a total of (5 + 4 + 3 + 2 + 1) + (4 + 3 + 2 + 1) + (3 + 2 + 1) + (2 + 1) + 1 = 35 possible combinations of a and d that form an A.P.
- Calculating the probability:
The probability of getting an A.P. is given by the ratio of favorable outcomes to total outcomes.
P(A.P.) = favorable outcomes / total outcomes
= 35 / 216
Simplifying the fraction, we get:
P(A.P.) = 5 / 36
Therefore, the correct answer is option D: 1/18.