the total number of barrels in 2000 was about 375 million. Calculate .25 × 375 =
93.75. (Why did we not type 375,000,000? Because we can add those zeroes
back on at the end and save our fingers from cramping.) In 2005, miscellaneous
vehicles again used about 25% of the total, but the line graph shows us that the
total has decreased to about 300 million. Let’s calculate .25 × 300 = 75. So the
decrease was 93.75 – 75 = 18.75. Now we can add on our zeroes to get our
proper answer: 18,750,000 barrels.
Do you mind if we add one final layer of complexity? Of course you don’t.
Circle Graphs
What’s the story? The pie chart below breaks down the fuel use of the various
types of miscellaneous vehicles by type, all in 2010. So in 2010, 33% of the fuel
used by miscellaneous vehicles was used by Segways; 13% was used by Jet
Skis, etc.