Capgemini
Company
Numerical Ability
Time Distance and Speed
In a race from pt. X to pt Y and back, Jack averages 30miles/hr to pt 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 tym,
who’ll finish 1st
Read Solution (Total 5)
-
- The Average speed of Jack is 15mph by 2xy/x+y.
and sandy is 20miles/hr...
by comparing both speed sandy will reach first.. - 12 years agoHelpfull: Yes(40) No(3)
- jack's average speed will be (30+10)/2=20 miles/hr
since he covered same distance both times
so, both will reach same time at the finish - 12 years agoHelpfull: Yes(0) No(27)
- at same time since distance and time is same
avg=s1+s2/2
- 8 years agoHelpfull: Yes(0) No(0)
- let D=60Km
jack avg time= 60/30+60/10=2+6=8
sandy avg time=60/20+60+20=3+3=6
thus, sandy will finish first. - 8 years agoHelpfull: Yes(0) No(0)
- 3 answers · Geography
Best Answer
They will tie. 30 one way and 10 the other is an average of 20, same as Sandy.
trea0766 · 1 decade ago
Comment 1 5
Answers
To solve this we can just make a "guess" which will make this a little simpler...we can just "guess" that the distance is 1 mile from X to Y...this way we will be working with easier numbers.
First Jack
X->Y
If the distance is 1 mile and Jack can run for 30 miles in 1 hour we can see that it would take jack 2 minutes to get there [1 mile*(1 hour/30 miles)*(60 minutes/1hour)] = 2 minutes.
Y->X
If he can run 10 mph on the way back then it would be [1 mile*(1 hour/10 miles)*(60 minutes/1hour)] = 6 minutes.
The total time taken it is 8 minutes.
Sandy
If she can run 20 mph on the way back then it would be [1 mile*(1 hour/20 miles)*(60 minutes/1hour)] = 3 minutes.
and she does that twice so it takes her 6 minutes.
It takes Jack 8 minutes and it takes Sandy 6 minutes...so Sandy finishes first. - 6 years agoHelpfull: Yes(0) No(0)
Capgemini Other Question