1) When we have grouped data, we do not have the exact values for the data. This means that we are unable to work out the exact mean and instead can only find an estimate for the mean.

2)

a) Mean = 2,500 g

2)

a) Mean = 2,500 g

b) Modal class = 2,000 ≤

c) 2,000 ≤

3)

a) Mean = 108 minutes

*w*< 3,000c) 2,000 ≤

*w*< 3,0003)

a) Mean = 108 minutes

b) Modal class = 80 ≤

c) 80 ≤

4)

a) Mean = 41

*m*< 120c) 80 ≤

*m*< 1204)

a) Mean = 41

b) Modal Class = 40 ≤

c) 30 ≤

*t*< 60c) 30 ≤

*t*< 40**Working**

**Questions**

You may use a calculator for the following questions. Click here for a printable version of the data and tables.

1) When we are working with grouped data, why do we find an estimate for the mean rather than the actual mean?

2) The data below shows the weight of new born babies.

a) Fill in the table and find an estimate for the mean.

b) What is the modal class?

c) Which class contains the median?

3) The data below shows the number of minutes that people spend in a car in one week.

b) What is the modal class?

c) Which class contains the median?

3) The data below shows the number of minutes that people spend in a car in one week.

a) Fill in the table and find an estimate for the mean. Give your answer to the nearest integer.

b) What is the modal class?

c) Which class contains the median?

4) The data in the table below is for the amount of time spent revising for an exam.

b) What is the modal class?

c) Which class contains the median?

4) The data in the table below is for the amount of time spent revising for an exam.

a) Fill in the table and find an estimate for the mean. Give your answer to the nearest integer.

b) What is the modal class?

c) Which class contains the median?

b) What is the modal class?

c) Which class contains the median?