Fill in the blanks to make the following statements correct.

a. It is difficult to compare two or more data series when absolute numbers and different units are used. For that reason we construct ___________ numbers in order to compare ___________ changes.

b. To construct an index number for computer prices over time, we divide the ___________ in the given period by the ___________ in the base period and multiply by 100.

c. The best way to display and compare the national income in each of the 10 largest economies in the world is a ___________ graph.

d. The best way to display data showing national income and investment spending across 50 countries for 2018 is a ___________ diagram.

e. The best way to display national income in Canada over the last 25 years is a ___________ graph.