Question

A bag contains 10 discs.
Each disc is labelled with a different number from 1 to 10
Adinis chosen from the bag at random
Write down the probability that the chosen disc is
(a) the number 3
(b) a number loss than four
(c) a square number
(d) a prime number
Help please !!!

Answer 1

Answers:

• (a) 1/10
• (b) 3/10
• (c) 3/10
• (d) 2/5

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Explanations:

Part (a)

There is only one disc labeled "3" out of 10 total. So we end up with the probability 1/10.

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Part (b)

The list of numbers less than 4 are {1,2,3} which are 3 items out of 10 discs. We end up with 3/10.

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Part (c)

A square number, aka a perfect square, smaller than 10 is the list {1,4,9}

Since 1 = 1^2, 4 = 2^2 and 9 = 3^2

Like part (b), we end up with the same result of 3/10.

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Part (d)

The list of primes smaller than 10 is {2, 3, 5, 7}. Notice that 1 is not prime.

So we end up with 4/10 = 2/5.