To read the line plot in order to answer this question, you will need to understand that each X above the numbers represents the number of hours 1 student studied. If you count the total number of Xs, that would represent the total number of students surveyed.
The number of students that studied at least four hours, would be the number of Xs that are at 4 or above. This means there were 4 students that studied for hours or more.
(1)
we are given
U is the midpoint of RS
and we have

so, we can use formula

we can plug values

............Answer
(2)
V is the midpoint of ST
so, we get

now, we can plug values

divide both sides by 2
.........Answer
(3)
now, we can find y
W is the midpoint of TR
so, we get

we can plug value

divide both sides by 3

(4)
we can see that
triangles URW and RST are similar
so, their sides ratios must be equal
so, we get

we can plug values



...........Answer
(5)
we can see that
triangles SUV and RST are similar
so, their sides ratios must be equal
so, we get

now, we can plug values


.............Answer
The answer to this question is 2