Answer: 2.76 g
Step-by-step explanation:
The formula to find the standard deviation:-

The given data values : 560 g, 562 g, 556 g, 558 g, 560 g, 556 g, 559 g, 561 g, 565 g, 563 g.
Then, 
Now, 
Then, 
Hence, the standard deviation of his measurements = 2.76 g
1) y= - 2x² + 8x. It's a parabola open downward (a<0)
2) x - 2.23.y + 10.34 = 0 . Re-write it : y = (x/2.23) + (10.34/2.23), a linear equation.
To find the intersections between 1) & 2), let 1) = 2)
-2x² + 8x = (x/2.23) + (10.34/2.23)
-2x² + 8x - (x/2.23) - (10.34/2.23) =0 ; solve this quadratic for x values:
x' (that is A) = 0.772 & x" (that is B) = 3. (these are the values of x-intercept (parabola with line). To calculate the y-values, plug x' & x' in the equation:
for x' = 0.772, y = 0.34 → B(0.772 , 0.34)
for x" = 3, y = 0.016 → A(3 , 0.O16)
So B IS AT 0.34 Unit from the ground
90 round to the nearest hundredth