To compute the mean, you simply have to sum all the elments in the data set and the divide the sum by the number of elements:
To compute the variance, we first need to compute the distance of each element from the mean. To do so, we build a "parallel" dataset, given by the difference of every value and the mean:
Now we need those difference squared:
The variance is the mean of this new vector, so
Finally, the standard deviation is simply the square root of the variance, so you have
Answer:
(a) D(t)= -4.9 t^2 + vt
(b) 10 sec
(c) 122.5m
(d) At t= 4sec, v= 9.8m/s (upwards) and at t= 9sec, v= 39.2m/s (downwards)
(e) -24.5m
(f) -49m/s (i.e. downwards)
(g) 0
Step-by-step explanation:
(b) Time in the air = 2v/g = 10sec
(c) Maximum height = =122.5m
(d) Velocity at any time t = v -9.8t
So, at t= 4sec, velocity = 49 – 9.8(4) =9.8m/s
at t= 9sec, velocity = 49 – 9.8(9) = -39.2m/s
(e) Average velocity = = -24.5m
(g) the stone is thrown vertically upwards, so no horizontal distance covered.