JAMB - Mathematics (2013 - No. 24)
The mean of seven numbers is 10. If six of the numbers are 2, 4, 8, 14, 16 and 18, find the mode.
6
8
14
2
Explanation
Using x = \(\frac{\sum x}{N}\) in each case, we get;
\(\sum_{6}^{i=1} x_i\) = 10 x 7 = 70
\(\sum_{7}^{i=1} x_i\) = 2 + 4 + 8 + 14 + 16 + 18 = 62
Hence the missing number can be obtained from
\(\sum_{6}^{i=1} x_i - \sum_{7}^{i=1} x_i\) = 70 - 62 = 8
So, all the seven numbers are 2, 4, 8, 8, 14, 16, 18
Mode = 8
\(\sum_{6}^{i=1} x_i\) = 10 x 7 = 70
\(\sum_{7}^{i=1} x_i\) = 2 + 4 + 8 + 14 + 16 + 18 = 62
Hence the missing number can be obtained from
\(\sum_{6}^{i=1} x_i - \sum_{7}^{i=1} x_i\) = 70 - 62 = 8
So, all the seven numbers are 2, 4, 8, 8, 14, 16, 18
Mode = 8
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