Problem Professor Snodgrass has a theory that right after a lawn is mowed, its probability density looks like: That is, ${1\over 2}$ for $5<length<7$, and 0 everywhere else. What's the probability that a blade of grass you measure will have a length between $2.5$ and $3$? How about between $5.5$ and $5.75$? How about between $5.5$ and $5.51$? Hint: if this isn't completely obvious to you, then read on and answer it later.