Find the mean deviation of 1, 2, 3 and 4

Step 1: Analyze the question Mean deviation is the average of the absolute distances of each value from the mean.

Step 2: The concept Mean deviation = Σ|x − x̄| / n

Step 3: Solution

Mean: x̄ = (1 + 2 + 3 + 4) / 4 = 10/4 = 2.5

Absolute deviations:

• |1 − 2.5| = 1.5
• |2 − 2.5| = 0.5
• |3 − 2.5| = 0.5
• |4 − 2.5| = 1.5

Sum = 1.5 + 0.5 + 0.5 + 1.5 = 4

Mean deviation = 4 / 4 = 1.0

Step 4: Answer The mean deviation is 1.0, which matches option A.

Tip: Always find the mean first, then take the absolute value of each difference (ignore negative signs). If you forget the absolute value, the deviations just sum to zero. Also, 2.5 in the options is the mean, not the mean deviation, so don't fall for that distractor.