D/S word+rate

ska7945 wrote:For each landscaping job that takes more than 4 hours, a certain contractor charges a total of r dollars for the first 4 hours plus 0.2r dollars for each additional hour or fraction of an hour, where r > 100. Did a particular landscaping job take more than 10 hours?
(1) The contractor charged a total of $288 for the job.
(2) The contractor charged a total of 2.4r dollars for the job.

(1) it's possible that r=288, in which case the job took less than 10 hours. It's also possible that r=101 in which case the job took more than 10 hours: insufficient.

(2) we know that 1r represents 4 hours and each .2r represents another hour (or fraction of an hour).

So, if the charge is 2.4r, we know that:

1r = 4 hours
1.2r = 6hours
.2r = at least a fraction of another hour

So, the minimum time spent is 4 + 6 + a bit which is definitely greater than 10.. sufficient!

(2) is suff, (1) is insuff: choose (b).