A and B throw with one die for a stake of Rs 11 which is to be won by ...
Probability of obtaining 6 in a single throw is 1/6. Probability that A wins the stake if he get 6 in first throw or if he loses then B also lose and then he get 6 in his second throw i.e. overal 3
rd throw and so on.
[sum of infinite terms of G.P.]
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A and B throw with one die for a stake of Rs 11 which is to be won by ...
Probability of obtaining 6 in a single throw is 1/6. Probability that A wins the stake if he get 6 in first throw or if he loses then B also lose and then he get 6 in his second throw i.e. overal 3
rd throw and so on.
[sum of infinite terms of G.P.]
A and B throw with one die for a stake of Rs 11 which is to be won by ...
Given:
A and B are playing a game where they throw a die for a stake of Rs 11. The player who first throws a 6 wins the stake. A has the first throw.
To find:
The expectation of A winning the stake.
Solution:
Step 1: Determine the probability of A winning on the first throw.
- The probability of A throwing a 6 on the first throw is 1/6, as there is only one favorable outcome (getting a 6) out of the six possible outcomes of throwing a die.
Step 2: Determine the probability of A winning on the second throw.
- If A does not win on the first throw, the game moves to B.
- The probability of B not winning on the first throw is 5/6, as there are five possible outcomes (1, 2, 3, 4, 5) out of six which are not favorable for B winning.
- If B does not win on the first throw, the game moves back to A.
- The probability of A winning on the second throw is the same as the probability of A winning on the first throw, which is 1/6.
Step 3: Determine the probability of A winning on the third throw.
- If A does not win on the second throw, the game moves to B.
- The probability of B not winning on the second throw is 5/6.
- If B does not win on the second throw, the game moves back to A.
- The probability of A winning on the third throw is the same as the probability of A winning on the first throw, which is 1/6.
Step 4: Determine the probability of A winning on the nth throw.
- Following the same pattern, the probability of A winning on the nth throw is (1/6)^n.
Step 5: Calculate the expectation of A winning the stake.
- The expectation (E) of A winning the stake is given by the formula:
E = (probability of A winning on the first throw) + (probability of A winning on the second throw) + (probability of A winning on the third throw) + ...
- Plugging in the values, we get:
E = (1/6) + (1/6)^2 + (1/6)^3 + ...
Step 6: Simplify the expectation.
- The expectation can be simplified using the formula for the sum of an infinite geometric series:
E = a / (1 - r)
- In this case, a = 1/6 (the first term) and r = 1/6 (the common ratio).
E = (1/6) / (1 - 1/6)
= (1/6) / (5/6)
= 1/5
Step 7: Simplify the expectation to obtain the final answer.
- The stake is Rs 11, and the probability of A winning the stake is 1/5.
- The expected value of A winning the stake is given by:
Expected value = (probability of A winning) * (stake)
= (1/5) * (11)
=