January 2008 SAT Hard Math Question HELP #18

muhammad9211
Sat, 27 Jul 2013 12:11:35 +0000

U assumed he would convert time to minutes. Why assume he wont convert back. Time = 10 / 20 = 1/2. U converted that number to 30 min. U didnt convert back to hours. I think that numbet shouldnt even be converted in the first place. Total time is 3/4. Now apply formula s=d/t
S=20/(3/4)=80/3
Bottom line is both methods are correct. It depends on which ppl prefer. Whether they prefer using proportions which u should know many ppl do struggle with. Or applying a simple formula .