Question

Find the probability that a number selected at random from the numbers 1 to 25 is not a prime

number when each of the given numbers is equally likely to be selected.

#no irrelevant answer
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Answer 1

Favourable outcomes = {1,4,6,8,9,10,12,14,15,16,18,20,21,22,24,25}

Number of favourable outcomes=16

Number of total possible outcomes=25

p(not a prime) = (number of favourable outcomes) / number of total possible outcomes

=16/25

Answer 2

Given:

• A number is selected at random from the numbers 1 to 25.
• Each of the given numbers is equally likely to be selected.

To Find:

• Probability that the number is not a prime number.

Solution:

Required Sample space of the following event ( Non- prime numbers between 1 to 25 )

`\dashrightarrow` 1, 4, 6, 8,9 10,12, 14, 15, 16,18, 20, 21, 22, 24, 25

Number of Favourable Outcomes = 16

Total number of outcomes = 25

Now as we know

Probability of an event =

`\star\;\boxed{\sf{\pink{( Favourable\; number\;of\; outcomes)/(Total\; number\;of\; outcomes)}}}`

Probability = 16/25

Hence, probability that the number is not a prime number is 16/25.