January 2008 SAT Hard Math Question HELP #18

WorkOverTalent
Sat, 27 Jul 2013 21:17:51 +0000

Okay I think I understand it pretty well! Thank you Muhammed and JohnTee! I tried out both of your methods and they worked pretty well. So when I tried this today again. What I did was use RT=D and then I got 1/2 for the time it took for 20 miles and 1/4 for the time it took for 40 miles. Together thats 1/2 and 1/4. Since that is the total time I used fractions and added it to get 3/4;thus, giving you the time it took for both 20 miles. Since 20 miles is the total distance, TOTAL DISTANCE/TIME= AVG SPEED so 20/(3/4)= 80/3 or 26.667. Totally got it now. I guess it was the avg speed formula that threw me off guard. Xiggi, Im not fully understanding your method. If you could clarify on it, that would be great. Thank you guys so much! I appreciate it