Frequency Density Flashcards

All 6 cards in this deck

What is frequency density?

Frequency $\div$ class width.

How do you work out the class width of a group?

e.g. $20 < w \le 50$

Upper bound $-$ lower bound.

e.g. $50 - 20 = 30$

How do you get the frequency of a class from its frequency density?

e.g. frequency density $2.5$, class $70 < w \le 90$

Frequency $=$ frequency density $\times$ class width.

e.g. $2.5 \times 20 = 50$

What does the area of a bar in a histogram represent?

The frequency of that class.

True or false? In a histogram, the height of each bar shows the frequency of that class.

False. The height is the frequency density; the area of the bar shows the frequency.

True or false? A frequency density must be a whole number.

False. It is frequency $\div$ class width, so it can be a decimal, e.g. $50 \div 20 = 2.5$.