+0  
 
0
23
2
avatar

Sam left his school at 3:05. He walked at a speed of 3.5 mph. 15 minutes later, Al started running after him, and he caught up with Sam 20 minutes later. What was Al’s speed?

 Oct 11, 2020
 #1
avatar+27725 
+1

Sam has a 1/4 hr head start at 3.5 m/hr

3.5 m/h x 1/4 hr = .875 miles

 

Al closes this distance in 20 minutes = 1/3 hr

  he is thus moving     .875 m/1/3 hr   FASTER than Sam = 2.625 m/hr faster

      3.5 + 2.625 = 6.125 m/hr

 Oct 11, 2020
 #2
avatar
0

15 + 20 =35 minutes spend walking by Sam when Al caught up with him.

 

3.5 mph x 35/60 =2 1/24 =49/24 - miles covered by Sam


[49 / 24] / [20/60][Time spent jogging by Al] =6 1/8 mph - Al's jogging speed.

 Oct 11, 2020

33 Online Users