AI generatedStatisticsGCSE Higher / IGCSE Extended

Finding a missing frequency from a histogram

Finding a missing frequency from a histogram.

  • Use a known class to calibrate the scale: density = frequency ÷ class width.
  • Divide its density by the number of vertical grid spaces to find the scale per space.
  • Frequency = width × density. Use each class’s own width; add frequencies to find total.

Example 1

Find the frequency in .

Histogram: bar area represents frequency123456510152025300Frequency densityTime (minutes)
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.

Example 2

Find the frequency in . The class has frequency 45. First find the missing density scale.

Histogram: bar area represents frequencyk5101520253035400Frequency densityMass (g)
Known densityDivide the known frequency by its width.
Divide by the known bar’s number of vertical grid spaces.
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.

Your turn

Question 1

Find the frequency in .

Histogram: bar area represents frequency2468101210203040506070800Frequency densityLength (cm)
Check answer
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.
Question 2

Find the frequency in . The class has frequency 20. First find the missing density scale.

Histogram: bar area represents frequencyk5101520253035400Frequency densityTime (minutes)
Check answer
Known densityDivide the known frequency by its width.
Divide by the known bar’s number of vertical grid spaces.
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.
Question 3

Find the frequency in .

Histogram: bar area represents frequency1234567510152025300Frequency densityMass (g)
Check answer
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.
Question 4

Find the frequency in . The class has frequency 180. First find the missing density scale.

Histogram: bar area represents frequencyk10203040506070800Frequency densityLength (cm)
Check answer
Known densityDivide the known frequency by its width.
Divide by the known bar’s number of vertical grid spaces.
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.
Question 5

Find the frequency in .

Histogram: bar area represents frequency123456785101520253035400Frequency densityTime (minutes)
Check answer
Required densityRead the target height using the calibrated scale.
Required frequencyMultiply this class’s width by its density.
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