The mean of the numbers 2, 5, 2x and 7 is less than or equal
MATHEMATICS
WAEC 2010
The mean of the numbers 2, 5, 2x and 7 is less than or equal to 5. Find the range of the values of x
- A. x \(\leq\) 3
- B. x \(\geq\) 3
- C. x < 3
- D. x > 3
Correct Answer: A. x \(\leq\) 3
Explanation
mean \(\leq\) 5; \(\frac{2 + 5 + 2x + 7}{4}\) \(\leq\) 5
= \(\frac{14 + 2x}{4} \leq 5\)
= 14 + 2x \(\leq\) 5 x 4
14 + 2x \(\leq\) 20 ; 2x \(\leq\) 20 - 14
2x \(\leq\) 20 - 14
2x \(\leq\) 6
x \(\leq\) \(\frac{6}{2}\)
x \(\leq\) 3
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