Question
The mean of a set of 15 numbers is 40. If the mean of
the initial 5 numbers in this set is represented by the expression (12x + 10), and the mean of the subsequent 10 numbers is given by (7x - 10), calculate the value of 'x'.Solution
Sum of first all 15 numbers = 40 X 15 = 600 Sum of first 5 numbers = 5 X (12x + 10) = (60x + 50) Sum of last 10 numbers = 10 X (7x - 10) = (70x - 100) So, we have 600 = 60x + 50 + (70x - 100) = 130x - 50 So, 130x = 600 + 50 = 650 So, x = (650/130) = 5 Therefore, the value of 'x' is 5.
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