JAMB - Mathematics (2002 - No. 39)
The mean of a set of six numbers is 60. If the mean of the first five is 50, find the sixth number in the set.
105
100
95
110
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Let the sum of the first five numbers and the sixth number be x and t respectively.
\(\frac{x + t}{6} = 60 \implies x + t = 360\)
\(\frac{x}{5} = 50 \implies x = 250\)
\(\therefore t = 360 - 250 = 110\)