Statistics & probability

To find the median, first arrange the numbers in ascending order: 1, 3, 4, 6, 8, 9. Because there is an even number of values, the median is the average of the two middle numbers, 4 and 6, which is 5. Option A is incorrect because 4 is just one of the middle values, not their average.

Since each coin toss is an independent event with a 1/2 probability of landing on heads, the probability of consecutive heads is 1/2 times 1/2, which equals 1/4. Option A is incorrect because 1/2 is only the probability of a single coin toss landing on heads.

To find the mean, sum the five numbers to get 50, then divide by the total count of 5, which yields 10. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option A is incorrect because 9 represents the median, or middle value of the data set, rather than the average.
• !Option A is incorrect because 1/2 is only the probability of a single coin toss landing on heads.
• !Option A is incorrect because 4 is just one of the middle values, not their average.
• !Option D is incorrect because 3/5 only compares red marbles to blue marbles instead of the entire total.

Answer each from memory — you'll see instantly whether you're right and why.

Run a focused 10-question mini-mock on Statistics & probability and see it stick.