Question

If the mean of five observations \( x, x+2, x+4, x+6, x+8 \) is 11, then the value of \( x \) is:

• A. \( 5 \)
• B. \( 6 \)
• C. \( 7 \)
• D. \( 8 \)

Hint:

For an arithmetic sequence, the mean is the middle term if the sequence has an odd number of terms.

Answer 1

The Correct Option is C

The mean formula is:
\[ \frac{\text{Sum of observations}}{\text{Total observations}}. \] \[ \frac{x + (x+2) + (x+4) + (x+6) + (x+8)}{5} = 11. \] \[ \frac{5x + 20}{5} = 11. \] \[ 5x + 20 = 55. \] \[ 5x = 35. \] \[ x = 7. \]