A and B play a game where each is asked to select a number from 1 to 25. If the two numbers match, both of them win a prize. The probability that they will not win a prize in a single trial, is:
Explanation
**Concept:**
• The **probability** of the occurrence of an event A out of a total possible outcomes N, is given by:
P(A)=Nn(A) , where n(A) is the number of ways in which the event A can occur.
• P(not A)=1−P(A)
• **Basic Principle of Counting:**
If there are m ways for happening of an event A, and corresponding to each possibility there are n ways for happening of event B, then the total number of different possible ways for happening of events A and B are:
○ Either event A alone **OR** event B alone: m+n
○ Both event A **AND** event B together: m×n
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**Calculation:**
The total number of possible pairs of selected numbers = N=25×25=625
If the numbers match, then both the numbers should be (1, 1), (2, 2), ... and so on.
Let's say that A is the event that both the selected numbers match.
The number of possible cases where the numbers match = n(A)=25
And,
P(A)=Nn(A)=62525=251
∴ Probability that the numbers will not match = 1−P(A)=2524
Hence, the probability of not winning a prize is 2524.