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JAMB Mathematics 2022 Paper

Question : 5

Total: 39

If the mean of 2, 5, (x+1), (x+2), 7 and 9 is 6. Find the median

Solution:

Concept:

Use the mean formula to find

x

, then arrange the data in ascending order and locate the median.

Explanation:

Mean

= \frac{\text{sum of values}}{\text{number of values}} = 6

So,

\frac{2 + 5 + (x+1) + (x+2) + 7 + 9}{6} = 6

Multiply both sides by 6:

2 + 5 + x + 1 + x + 2 + 7 + 9 = 36

Simplify:

2x + 26 = 36

2x = 10

x = 5

The numbers are:

2, 5, 6, 7, 7, 9

Median for 6 values is the average of the 3rd and 4th ordered values.

Median

= \frac{6 + 7}{2} = 6.5

Answer:

6.5

(Option C)

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