Statistics and probability

A random sample of people were asked "How many devices have you used to browse the internet in the last month?". The result are displayed in the graph.

How many people were surveyed?

• 50

• 57

• 42

• 61

The frequency table shows the number of cars owned by different families. Calculate the median.

• 1

• 4

• 10

• 5

A box plot has been drawn to show the heights of some petunia seedlings, in centimetres. Find the interquartile range.

• 6

• 11

• 7

• 8

The average height h of grass t days after being mowed, is shown in the table. Calculate the correlation coefficient r.

• 0.867

• 0.993

• 0.849

• 0.921

• 0.37

• 0

• 0.78

• 0.25

• 0.621

• 0.33

• 0.422

• 0.245

If 3 coins are tossed simultaneously, find the probability of getting exactly two tails.

One ball is drawn from each of the boxes shown. Find the probability that at most one blue ball is drawn.

If the correlation coefficient r = 0.98 then it refers to a ... correlation

• very strong

• weak

• moderate

• strong

The table shows the distribution of marks obtained on a test. Find the standard deviation of the test scores.

• 2.3

• 1

• 1.5

• 2