If the mean of the five observations x + 1, x + 3, x + 5, 2x + 2, 3x + 3 is 14, find the mean of first three observations.
Solution:
Mean of the five observations
x + 1, x + 3, x + 5, 2x + 2, 3x + 3 is 14
Mean = (x + 1 + x + 3 + x + 5 + 2x + 2 + 3x + 3)/5
= (8x + 14)/5
(8x + 14)/5 =14
8x + 14 = 70
8x = 70 – 14 = 56
x = 56/8 = 7
Mean of x + 1 + x + 3 + x + 5
Mean = (x + 1 + x + 3 + x + 5)/3
= (3x + 9)/3
= x + 3
Substituting the value of x
= 7 + 3
= 10
Therfore, the mean of first three observations is 10.
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