Pie Charts

Rules

“Pie charts” indicate fractions of a total. The larger the “slice” the greater the fraction.

The chart below, for example, shows the fraction of flights taken to Buffalo as opposed to Syracuse, Albany, and New York City.

Chart-reading is usually fairly easy. Most question trip-ups involve manipulating the data in the chart.

Practice

1. Approximately what percentage of the flights taken by LJ Air are bound for Albany, Buffalo, and Syracuse, respectively?

2. How many more flights would have to be taken to New York City for such flights to make up 60% of the total flights?

Comments

Answers to Practice Questions

1. Albany, Buffalo, and Syracuse, respectively, make up roughly 27%, 13%, and 11% of flight departures. The numbers above in the chart are not percentages but rather absolute numbers. There are a total of 93 flights, meaning the percentages are the flights to these three cities - 25, 12, and 10 - respectively.

2. There are a total of 93 flights of which 46 are currently bound for New York City. The amount of increase necessary to raise this proportion to 60% can be solved using algebra. Let i equal the necessary increase to raise it to 60%.

= .6 Take the initial equation.

 i + 46 = .6(i + 93)		Multiply both sides by (i + 93).

 i + 46 = .6i + 55.8		Expand the parentheses.

 i = .6i + 9.8			Subtract 46 from both sides.

.4i = 9.8 Subtract .6i from both sides.

 i = 24.5			Divide both sides by .4.

Approximately 25 flights are needed to increase the percentage to 60%.