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WAEC Mathematics 2014 Paper

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Question : 15

Total: 49

height	2	3	4	5	6
frequency	2	4	5	3	1

The table shows the distribution of the height of plants in a nursery. Calculate the mean height of the plants.

3.8
3.0
2.8
2.3

Solution:

Concept:

Mean of grouped data is calculated by dividing the sum of

f \times x

by the total frequency.

Explanation:

Height values are

x = 2, 3, 4, 5, 6

.

Their frequencies are

f = 2, 4, 5, 3, 1

.

Total frequency,

\sum f = 2 + 4 + 5 + 3 + 1 = 15

.

Now compute

fx

for each height:

2 \times 2 = 4

3 \times 4 = 12

4 \times 5 = 20

5 \times 3 = 15

6 \times 1 = 6

So

\sum fx = 4 + 12 + 20 + 15 + 6 = 57

.

Mean,

\overline{x} = \frac{\sum fx}{\sum f} = \frac{57}{15} = 3.8

.

Answer:

The mean height is

3.8

.

Correct option: A.

3.8

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