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Jim has arrived late for his golf tee time with his friends.

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Jim has arrived late for his golf tee time with his friends. [#permalink]

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12 Jul 2012, 20:33
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Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

A. 1.8 yards per second
B. 2.0 yards per second
C. 2.4 yards per second
D. 2.7 yards per second
E. 3.0 yards per second

This is a question from a Kaplan diagnostics test (free online).
1) How long can you solve this for?
2) How do you approach this type of questions?
3) Can you point me to other similar distance problems?
[Reveal] Spoiler: OA

Last edited by Bunuel on 13 Jul 2012, 00:46, edited 2 times in total.
Edited the question.
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Re: Jim has arrived late for his golf tee time with his friends [#permalink]

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12 Jul 2012, 22:28
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stoy4o wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

1.8 yards per second
2.0 yards per second
2.4 yards per second
2.7 yards per second
3.0 yards per second

Hi,

The question involves the concept of relative speed and average speed,
To find the average speed, we have to find the total distance traveled and the total time taken:

Jim covers the total trip in two parts:
Part 1: Travelling on cart @ 4 yards/sec
Time taken by Jim to meet his friends = $$\frac {distance}{rel. speed}$$ = $$\frac{180}{4-1.5}$$
= 72 sec
Distance traveled = 4*72 = 288 yards
Part 2: Jim travels 120 yards @ 1.5 yards/sec
time taken = $$\frac {120}{1.5}$$ = 80 secs

Total distance travelled = 288 + 120 = 408
Total time taken = 72 + 80 = 152
Thus, average speed = $$\frac {408}{152}$$ = 2.68 ~ 2.7 yards/sec

It took me 2 minutes to solve & 10 mins to write here.

Regards,
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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13 Jul 2012, 01:00
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stoy4o wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

A. 1.8 yards per second
B. 2.0 yards per second
C. 2.4 yards per second
D. 2.7 yards per second
E. 3.0 yards per second

This is a question from a Kaplan diagnostics test (free online).
1) How long can you solve this for?
2) How do you approach this type of questions?
3) Can you point me to other similar distance problems?

Jim's rate: 4 yards per second;
Friends' rate: 1.5 yards per second;
Their relative rate: 4-1.5=2.5 yards per second.

To cover the distance of 180 yards between them $$\frac{180}{2.5}=72$$ seconds are needed. Distance covered by Jim is $$4*72=288$$ yards.

To cover the next 120 yards Jim will need $$\frac{120}{1.5}=80$$ seconds.

$$Average \ rate=\frac{total \ distance}{total \ time}=\frac{288+120}{72+80}\approx{2.7}$$.

DS questions on Distance/Rate: search.php?search_id=tag&tag_id=44
PS questions on Distance/Rate: search.php?search_id=tag&tag_id=64

Hope it helps.
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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13 Jul 2012, 17:06
Thank you guys.

I appreciate it.
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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23 Feb 2013, 17:52
can someone explain why relative speed is used here, ie 4 - 1.5 to get 2.5 yard per s
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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25 Feb 2013, 15:02
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When Jim arrives he finds that his friends are 180 yards ahead of him and are still walking at a rate of 1.5 yards/sec. However, he gets a ride in a golf cart and is able to travel at a speed of 4 yards/sec. During this time, his friends are still walking at a speed of 1.5 yards/sec. Thus, the distance between them will get reduced at a rate of 4-1.5=2.5 yards/sec. The time taken to cover the distance of 180 yards is effectively increased and hence we use the relative speed to calculate the time.

Consider this situation for example. You are walking with your friend when suddenly you meet someone and stop to talk to the person. Meanwhile your friend continues walking. After you end the conversation, you run to catch up with your friend. However, your friend continues to walk. Wouldn't this increase the time taken to reach your friend as opposed to the time taken if he waited for you when you start running? What is the reason for this increase in time? This is because even though you are running, your friend is also walking in the same direction and thus the distance between you is reducing at a slower rate than it would if he waited for you. Thus, you need to calculate the relative speed to account for this.

Hope this helps! However, if you have any further concerns, please let me know.

lemonhalls wrote:
can someone explain why relative speed is used here, ie 4 - 1.5 to get 2.5 yard per s
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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25 Feb 2013, 20:03
lemonhalls wrote:
can someone explain why relative speed is used here, ie 4 - 1.5 to get 2.5 yard per s

The concept used here is relative speed. When two objects move in the same direction, one going faster than the other, the speed of the one going faster relative to the one going slower is the difference of the speeds.
Check out this post I wrote sometime back on relative speed to get a hang of the basic concept. The answer explanation will make a lot of sense thereafter.

http://www.veritasprep.com/blog/2012/07 ... elatively/
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Get started with Veritas Prep GMAT On Demand for $199 Veritas Prep Reviews Intern Joined: 27 Dec 2012 Posts: 41 Re: Jim has arrived late for his golf tee time with his friends. [#permalink] Show Tags 13 Mar 2013, 23:41 Hi karishma, I understand the concept of relative speed. However cant we solve this question with the approach outlined below?? The time when jim travels the 180 miles in cart is 45 seconds i.e. 180/4. In these 45 seconds his freinds travel a further 1.5*45 miles. So jim has to travel a total of 180+67.5 miles at a speed of 4 yards/mile to meet his friends. But by using this approach i am getting the answer as 2.59 approx. What am i missing. Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 7875 Location: Pune, India Re: Jim has arrived late for his golf tee time with his friends. [#permalink] Show Tags 14 Mar 2013, 00:08 2 This post received KUDOS Expert's post sauravleo123 wrote: Hi karishma, I understand the concept of relative speed. However cant we solve this question with the approach outlined below?? The time when jim travels the 180 miles in cart is 45 seconds i.e. 180/4. In these 45 seconds his freinds travel a further 1.5*45 miles. So jim has to travel a total of 180+67.5 miles at a speed of 4 yards/mile to meet his friends. But by using this approach i am getting the answer as 2.59 approx. What am i missing. What happens in the time that Jim travels the 67.5 yards? During that time, his friends go further ahead at the speed of 1.5 yards/s and he still doesn't catch up with them. Time taken by Jim to cover 67.5 yards is 67.5/4 = 16.875 secs So the friends have traveled another 1.5*16.875 yards So it is best to use the relative speed concept. Jim has to cover 180 yards (relatively) at a relative speed of 4 - 1.5 = 2.5 yards/sec. Think of it like this: Out of his speed of 4 yards/sec, he uses 1.5 yards/sec to cover whatever distance his friends are covering now and the rest 2.5 yards/sec he uses to cover the gap of 180 yards between them. Time taken by Jim to meet his friends = 180/2.5 = 72 secs Time for which he travels at 1.5 yards/sec = 120/1.5 = 80 secs Average speed will be close to the middle of 1.5 and 4 but closer to 1.5 (using weighted averages). Middle of 1.5 and 4 is 2.75 so it will be 2.7 yards/sec _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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14 Mar 2013, 00:22
Now i understand. Thank you so much karishma. Your explanations are the best I have encountered on this forum.
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Jim has arrived late for his golf tee time with his friends [#permalink]

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07 Oct 2013, 22:20
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Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

1.8 yards per second
2.0 yards per second
2.4 yards per second
2.7 yards per second
3.0 yards per second
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Re: Jim has arrived late for his golf tee time with his friends [#permalink]

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07 Oct 2013, 22:50
good question. I tried solving it twice and got two different answers. Please post the OE when you think its appropriate. d Good qurestion +1 KUDOS.
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Re: Jim has arrived late for his golf tee time with his friends [#permalink]

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07 Oct 2013, 23:23
saintforlife wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

1.8 yards per second
2.0 yards per second
2.4 yards per second
2.7 yards per second
3.0 yards per second

Given Jim's friends has a lead of 180 yards and moving at 1.5 yards/sec speed
Jim on golf cart with speed 4 yards/sec has to meet this friends, assuming he meets them after "t" secs

So the total distance traveled by Jim and his friends should be same so as to meet them=> 180+1.5t=4t
=> 180=2.5t
=>72secs, so Jim meets his friends after traveling 72 secs at 4 yards/sec speed---First part of his journey (288 yards in 72 secs)
Now, Jim travels 120 yards with speed 1.5 yards/sec in 120/1.5=80 secs---second part of his journey (120 yards in 80 secs)

So avg speed of Jim= total distance traveled/ total time
=> (288+120)/(72+80)=408/152
=>2.7 yards/sec approx
Ans D..hope its clear
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Re: Jim has arrived late for his golf tee time with his friends [#permalink]

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07 Oct 2013, 23:32
saintforlife wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

1.8 yards per second
2.0 yards per second
2.4 yards per second
2.7 yards per second
3.0 yards per second

Merging similar topics. Please refer to the solutions above.
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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31 Dec 2013, 08:40
stoy4o wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

A. 1.8 yards per second
B. 2.0 yards per second
C. 2.4 yards per second
D. 2.7 yards per second
E. 3.0 yards per second

This is a question from a Kaplan diagnostics test (free online).
1) How long can you solve this for?
2) How do you approach this type of questions?
3) Can you point me to other similar distance problems?

Very nice question. Similar to Manhattan's GMAT 'Moving walkway'

Let's get this started

First, relative rate 4-1.5=2.5 yards per second to catch up with his buddies

Therefore, time will be 180/2.5 =360/5=72 seconds

Now in 72 seconds he traveled= 72*4 = 288 yards

Now, he will travel the next 120 yards in = 120/1.5 = 240/3 in 80 seconds

Hence average speed will be 288+120 / 80+ 72 = 2.7

Kudos if it helps

Cheers!
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25 Feb 2015, 23:23
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Jim has arrived late for his golf tee time with his friends. [#permalink]

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12 Dec 2015, 14:23
d=distance walked by J's friends from 180 yards to where J overtakes them
(180+d)/4=d/1.5
d=108
total distance for J=180+108+120=408 yards
total time for J=(180+108)/4+120/1.5=152 seconds
408/152=2.7 yards per second average speed
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Re: Jim has arrived late for his golf tee time with his friends. [#permalink]

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12 Dec 2015, 17:40
Average Speed = Total Distance / Total Time

Distance 1 = 180
Distamce 2 = 120

Time 1 = 180/Relative Speed of Jim = 180/(4 - 1.5) = 180/2.5 = 72
Time 2 = 120/Speed of Group = 120/1.5 = 80
Total Distance = 300 Yards
Total Time = 80+72 = 152 seconds
Hence Average Speed apprx 2 / second

My 2 cents on problem solving
Introduce numbers as late as possible into the calculation
Solve it in equation format, use cancellation of terms etc
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05 Aug 2017, 04:21
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Jim has arrived late for his golf tee time with his friends. [#permalink]

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05 Aug 2017, 16:21
stoy4o wrote:
Jim has arrived late for his golf tee time with his friends. When he arrives at the course, he discovers that his friends have already walked 180 yards ahead on the course and that they are continuing to walk forward at a rate of 1.5 yards per second. A bystander with a golf cart takes pity on Jim and drives him to meet his friends at the rate of 4 yards per second. Once Jim meets his friends, he exits the cart and walks with them at their rate for the next 120 yards. What is Jim’s approximate average speed for his total trip?

A. 1.8 yards per second
B. 2.0 yards per second
C. 2.4 yards per second
D. 2.7 yards per second
E. 3.0 yards per second

let d=distance from 180 yards to point where J meets friends
(180+d)/d=4/1.5
d=108 yds
108+180+120=408 total yds
(180+108)/4 yps=72 sec
120/1.5 yps=80 sec
72+80=152 total seconds
408 total yds/152 total sec≈2.7 yps average speed for total trip
D
Jim has arrived late for his golf tee time with his friends.   [#permalink] 05 Aug 2017, 16:21
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