The answer is the first one.
Knowing that population density is like a rate, people per a given area, you would take the amount of people and divide by the area.
3.11E7/7.69E6 = 4.02 people per km squared.
Also the “E” is another way to write times 10 to a power and I recommend using that notation when plugging it into a calculator.
K.E=0.5mv^2
GPE=mgh
The child has both K.E and GPE
g is taken as 9.81
I believe it would be 160000
Under 45 mins is roughly 16%. This is because 68% of the curve exists within 1 SD of the mean. So 16% must be outside and smaller and 16% outside and larger (on average).
It is impossible to determine how likely you are to find someone with exactly the second amount. However, if you are looking for that or less, you would get 84%
