In a race from point t. X to point Y and back, Jack averages 30miles/hr to point Y and 10 miles/hr back
to pr X.Sandy averages 20 miles/hr in both directions. If Jack and Sandy start race at same time,
who’ll finish 1st

• The Average speed of Jack for covering a distance is 15miles/hr (based on 2xy/x+y)
  and that of sandy is 20miles/hr...so sandy speed is more hence if they start at same time Sandy reaches First...
• 11 years agoHelpfull: Yes(29) No(1)
• Apply (2xy)/(x+y) then jack's avg speed is 15miles/hr and sandy's avg speed is 20miles/hr...Hence sandy will finish first...
• 11 years agoHelpfull: Yes(15) No(1)
• Let the distance b/w X and y is 60 miles.
  Time taken by Jack frm X to y is 2 hrs.
  Time taken by Jack frm Y to X is 6hrs.
  Total time taken by jack is 6+2=8hrs.
  
  Now time taken by sandy frm x to y is 3 hrs
  and for y to X is also 3hrs
  Total time taken by sandy is 6 hrs..
  there fo sandy will finish first .
• 10 years agoHelpfull: Yes(3) No(0)
• Jack will finish first because the avg speed for him in both directions is more than Sandy's which we can calculate using 2xy/x+y
• 10 years agoHelpfull: Yes(0) No(3)