Histograms are used when class intervals are unequal. Frequency is represented by the area of the bar; the height of each bar is called the frequency density and there are no gaps between the bars.

1

A study surveys some families and constructs a histogram of how much they each spend on food in a week. 20 families spend between £20-£30. Estimate how many families spend over £40.

2

This table shows how much exercise, e, a group of students do per week, use it to draw a histogram: Hours of exercise, Frequency; 0<e≤0.5, 5; 0.5<e≤1.5, 15; 1.5<e≤2.5, 20. 2.5<e≤4, 11.

3

Adam surveys the distance, d, travelled to school by his classmates, use the results to construct a histogram: Distance (km), Frequency; 0.5<d≤1, 9; 1<d≤1.8, 15; 1.8<d≤2, 6; 2<d≤2.5, 10.

4

This is a table representing the ages, a, of people who visit a park, use it to construct a histogram: Age (years), Frequency; 5<a≤8, 7; 8<a≤12, 14; 12<a≤16, 9; 16<a≤20, 18.

5

The number of cars parked per day in a month in a parking lot, with space for 50 cars, is shown in this histogram; estimate on how many days the parking lot was 80% full or more.