Question

The algebraic sum of deviations of 30 observations measured from 20 is 3. The arithmetic mean of the observations is

• A. 20
• B. 20.1
• C. 20.01
• D. 21

Answer 1

Answer:

B. 20.1

$Σ_{i=1}^{30}(x_i-20)=3$

$x_i-Σ20=3$

$x=\frac{Σx_i}{n}$

$Σx_i=3+30 \times 20 =603$

$x=\frac{603}{30=20.1$