WAEC 2014 Mathematics · Question 43

c c height 2 3 4 5 6 frequency 2 4 5 3 1 The table shows the distribution of the height of plants in a…

Question

height23456frequency24531\begin{array}{c|c}height & 2 & 3 & 4 & 5 & 6 \\ \hline frequency & 2 & 4 & 5 & 3 & 1 \end{array} The table shows the distribution of the height of plants in a nursery. Calculate the mean height of the plants.

  1. A.3.8
  2. B.3.0
  3. C.2.8
  4. D.2.3

Answer: A. 3.8

Explanation written with AI and checked against the answer key

Analyze the question: We need the mean of a frequency distribution. Each height is weighted by how many plants have that height.

Concept: Mean = Σfx ÷ Σf

Solution:

| Height (x) | Frequency (f) | fx | |---|---|---| | 2 | 2 | 4 | | 3 | 4 | 12 | | 4 | 5 | 20 | | 5 | 3 | 15 | | 6 | 1 | 6 |

  • Σf = 2 + 4 + 5 + 3 + 1 = 15
  • Σfx = 4 + 12 + 20 + 15 + 6 = 57

Mean = 57 ÷ 15 = 3.8

Answer: The mean height is 3.8, which is option A.

Tip: Always build an fx column and add it up carefully. A quick check is that the mean must lie between the smallest and largest values (2 and 6). Since most of the frequency sits around 3 and 4, an answer near 3.8 is sensible.

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