Histograms
The question
How many are under 120?
Standing long jump (cm)
How it works.
bands:100–109110–119120–129130–139140–149
100–109:6 jumps
110–119:3 jumps
120–129:3 jumps
130–139:1 jumps
140–149:1 jumps
100–109:6 jumps
110–119:3 jumps
120–129:3 jumps
130–139:1 jumps
140–149:1 jumps
9
- 01
The bars touch, and that is the clue: this is not a bar graph of separate things, it is a number line cut into stretches of 10 cm. Each bar is a BAND, not a value.
- 02
So a bar's height counts how many fell ANYWHERE inside its band — the 100–109 bar says 6 jumps, but not what any single one of them was.
- 03
How many are under 120? Only the 100–109 and 110–119 bands count — 6 + 3 = 9 jumps. The 120–129 band falls on the other side of the line, so it is left out even though it is right next to it.