Answer:
(7)
error percentage is 0.6%
(8)
Graph-C
Explanation:
(7)
we are given cube
Let's assume edge of cube =x
so, volume of cube will be

we are given
V=125000
so, we can find 'x'


So,

now, we can use linear approximation formula


we have

we can plug a=50


we can find derivative

now, we can plug x=50


now, we can plug these values
and we get



so, error is

now, we can find percentage error
Percentage is

=0.6%
so, error percentage is 0.6%
(8)
we are given

We will find derivative
To get velocity , we will find derivative

we can use product rule
and we get

so, we get velocity equation as

now, we can draw graph
we can see that firstly , we get maxima and then minima
so, our graph would be
graph-C........Answer