#### Answer

a) 1
b)100
c)100
d)225

#### Work Step by Step

a) The area under the graph represents the probability, therefore it is 1(beacuse it includes all cases).
b)The median is the average of the 1 or 2 middle values, but this data is symmetric, therefore the mean is the median, therefore the median is 100.
c)The mode is the data occuring the most times, which here is 100 by looking at the graph.
d)variance is the square of the standard deviation:$variance=15^2=225.$