GCSE Mathematics (9-1)

25.2 Cumulative frequency — Practise with help

Warm-up: remember

  1. Find the median of 2,4,6,8,102,4,6,8,10.
  2. Add frequencies 3,7,43,7,4.
Feedback
  1. 66. 2. 1414.

Practise with help

Use this table: classes 0<t≤50<t\leq5, 5<t≤105<t\leq10, 10<t≤1510<t\leq15 have frequencies 3,6,53,6,5.

1. Find the cumulative frequency at each upper boundary.

Hint

Keep a running total, starting from the first frequency.

Step

The totals are 33, then 3+63+6, then 3+6+53+6+5.

Full working

The cumulative frequencies are 3,9,143,9,14.

2. State the coordinates to plot, including the starting point.

Hint

Pair each upper boundary with its cumulative frequency.

Step

Start at (0,0)(0,0), then use boundaries 5,10,155,10,15.

Full working

Plot (0,0),(5,3),(10,9),(15,14)(0,0),(5,3),(10,9),(15,14), then draw a smooth increasing curve.

3. Earlier work: the frequencies are 3,6,53,6,5. Which class has the greatest frequency?

Hint

Compare the three frequencies, not their running totals.

Step

The largest frequency is 66.

Full working

The class 5<t≤105<t\leq10 has the greatest frequency, 66.

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