A name is picked at random from a list of 50 girls and 50 boys - Junior Cycle Mathematics - Question 7 - 2014

There are 2 outcomes when tossing a fair coin: heads or tails. Therefore, the probability of getting heads is:

$P(B) = \frac{1}{2} = 0.5$

A standard deck has 52 cards, and there are 13 diamonds. Thus, the probability of drawing a diamond is:

$P(C) = \frac{13}{52} = 0.25$

There are 7 days in a week, and all 7 contain the letter 'a'. Therefore, the probability is:

$P(D) = \frac{7}{7} = 1$

From the set {1, 2, 3, 4, 5, 7, 11, 13}, the prime numbers are {2, 3, 5, 7, 11, 13}, which totals 6. Thus, the probability of choosing a prime number is:

$P(E) = \frac{6}{8} = 0.75$

The events can be positioned on the scale as follows:

• C: 0.25
• B: 0.5
• A: 0.5
• E: 0.75
• D: 1

An example is: Drawing a card that is a heart. The probability is:

$P = \frac{13}{52} = 0.25$

An example is: Picking an even number from the set {4, 6, 8}. Since all numbers are even, the probability is:

$P = \frac{3}{3} = 1$

With 3 possible answers and only one correct answer, the probability is:

$P = \frac{1}{3} = 0.3333$