Answer:
find the difference of points on the graph
Step-by-step explanation:
The cumulative frequency graph (CDF) represents the integral of the probability distribution function (PDF). You find the probability that X is in some interval by subtracting the value of the CDF at the low end of the interval from the CDF value at the high end of the interval.
p(a < x < b) = cdf(b) -cdf(a)
X=15-12
X=3(number of days in difference to the number of people)
X=9-3
X=6 it would take 6 days to cut the grass with 9 boys
I believe it is A. I did this awhile ago.