Worksheets · Foundation and Higher

Ordered stem-and-leaf, averages, spread and grouped means

3 exam-style questions. Answers and the mark for each step are on the last page.

Question 1Non-calculator · 1 mark
(a) A shop records the number of umbrellas sold each day. Number sold: 0, 1, 2, 3 Frequency: 3, 8, 5, 2 Work out the mode. (1)
Question 2Calculator · 3 marks
(a) Twenty students record how many books they finish in one month. Books finished: 0, 1, 2, 3 Frequency: 4, 9, 5, 2 Work out the mean number of books finished. (3)
Question 3Calculator · 3 marks
(a) Two groups of readings are combined. The first group contains n readings with mean 24. The second group contains n + 4 readings with mean 32. The mean of all the recorded readings is 29. One reading in the first group was recorded as 38, but should have been 14. Work out the mean of all the readings after this error is corrected. (3)

Answers and marks

(a) $1$

(a) $1.25$ books

P1 Establishing $0\times 4+1\times 9+2\times 5+3\times 2$ or an equivalent valid method.
P1 Establishing $25/20$ or an equivalent valid method.
A1 Correct answer: $1.25$ books

(a) $27.5$

Ordered stem-and-leaf, averages, spread and grouped means

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