Sampling and Mean, Mode and Median

The dot plot shows the ages of students in a school chess club.

Which of the following is NOT correct?

• 30 students were surveyed

• The range is seven years

• Twelve students were younger than 15

• The median age is 14.5

The median for the data 5, 5, 6, 7, 2 would be found by:

• adding all the results and multiplying by the number of results

• adding all the results and dividing by the number of results

• choosing the middle number

• ordering the results, then choosing the middle result

When finding the mean of a set of data:

• zeros do not matter at all

• zeros must be counted in the number of results

• zeros must be added to the total as they will change it

• any zeros will always make the mean zero

One extra number is added to the data set 3, 4, 6, 7, and this causes the mean to change to 8.

What is the number?

• 8

• 14

• 20

• 21

Which is the best description of the mode in a set of scores?

• The average of the scores

• The scores in the middle

• The difference between the highest and lowest score

• The score with the highest frequency

The tally shown gives the number of goals scored by a soccer team over a season. Which of the following is true?

• They have five games in which they scored one goal.

• In four of the games the team scored two goals.

• In the first game the team scored 5 goals.

• The total number of goals scored for the season was 10.

The median number of goals scored by the soccer team with these results is:

• 1

• 2

• 3

• 4

The chocolates in a bag are grouped by colour and the proportions shown in the pie graph.

If there are equal numbers of red and brown chocolates, how many are red, given that the bag contains 28 orange ones?

• 28

• 56

• 7

• 14

60% of population of people are known to have a European background. If a random sample of 30 people is drawn from that same population, how many of them would be expected to have a European background?

• 6

• 18

• 12

• 24

A random sample of 15 people detects 11 people who desperately need a holiday. If this sample is drawn from a population of 1350 people, how many people in the population are likely to desperately need a holiday?

• 900

• 940

• 990

• 1050