# Lesson: Introduction to GMAT Motion Questions

## Comment on Introduction to GMAT Motion Questions

### The easy questions in the

The easy questions in the example are much harder than the examples from the ones you did in the video. The explanations in the example question links aren't that clear. Do you have any other lessons to solve more complex problems for this topic?

Thanks

### This first lesson serves as

This first lesson serves as an introduction to motion problems. In total, there are 4 videos lessons on motion questions. So, if you're having difficulties with the linked questions above, you might want to watch all 4 lessons first and then return to these questions.

Awesome thanks

### https://gmatclub.com/forum

https://gmatclub.com/forum/donovan-and-michael-are-racing-around-a-circular-400-meter-track-if-d-193270.html

I didn't get the answer on this one. Is it a sound approach to assume that the time is constant and build a direct proportion between speeds &distances? s1/s2=d1/d2?

Thanks
Nisa

The two runners start at the same time.
Once Michael PASSES Donovan (i.e., laps Donovan), the clock stops.
So, each runner has the same TRAVEL TIME.

The only difference is their DISTANCES traveled.
At the point at which Michael PASSES Donovan, Michael has traveled 1 lap further than Donovan.

Here's my full solution that uses this concept: https://gmatclub.com/forum/donovan-and-michael-are-racing-around-a-circu...

Cheers,
Brent

### This is a retired GMAT rate

This is a retired GMAT rate-distance D/S question:

Stations X and Y are connected by two separate, straight, parallel rail lines that are 250 miles long. Train P and train Q simultaneously left Station X and Station Y, respectively, and each train traveled to the other's point of departure. The two trains passed each other after traveling for 2 hours. When the two trains passed, which train was nearer to its destination?

1. At the time when the two trains passed, train P had averaged a speed of 70 miles per hour.

2. Train Q averaged a speed of 55 miles per hour for the entire trip.

The answer is Statement 1 is sufficient. Could it be possible that Q was traveling faster and it passed P, which was traveling at 70 miles per hour? I thought Q's speed was needed for the answer to be sufficient?

Thanks.

### Hi Victoriano,

Hi Victoriano,
This is a tricky question!
Here's my full solution: https://gmatclub.com/forum/stations-x-and-y-are-connected-by-two-separat...

### Hi Sir,

Hi Sir,

Thank you for this lesson.

https://gmatclub.com/forum/annika-hikes-at-a-constant-rate-of-12-minutes-per-kilometer-she-197272.html

I have come across this problem, and could you please explain how we get
Let x = the additional # number of km she walks EAST before turning around.
This means the number of kilometers she will hike from this point = x + x + 2.75 kilometers

I don't understand why are there 2 x's verse just x + 2.75?

Is the first x the starting point to the 2.75 miles, and then the second x is the point where she keeps walking east until she has to go back in 45 minutes?

Thank you!

Let's say that, after walking EAST for 2.75 kms, Annika arrives at point P at 12:00pm.
She needs to return to the start of the trail by 12:45
START the timer at noon...

From here (point P), Annika will walk an additional x kilometers EAST until she arrives at point Q)
NOTE: Since we started the timer, Annika has now traveled x km

Upon arriving at Point Q, Annika will turn around and walk WEST until she reaches the start of the trail.
When Annika is at Point Q, her distance from the start of the trail = 2.75 + x km

So, starting at NOON, the total distance traveled = x + (2.75 + x)

Does that help?

Cheers,
Brent

### Hi Brent,

Hi Brent,

Could you please solve this question?
A certain experimental mathematics program was tried out in 2 classes in each of 32 elementary schools and involved 37 teachers. Each of the classes had 1 teacher and each of the teachers taught at least 1, but not more than 3, of the classes. If the number of teachers who taught 3 classes is n, then the least and greatest possible values of n are?

In the solution it said that we can see that 2(32) = 64 classes are taught by 37 teachers. Let k, m, and n be the number of teachers who taught, respectively, 1, 2, and 3 of the classes. One of the assumptions was that the one of the teachers could have not taught any class. Therefore the possible range starts from 0. Why are we assuming this?

Thanks

### Here's my full solution to

Here's my full solution to that question: https://gmatclub.com/forum/a-certain-experimental-mathematics-program-wa...

Q: One of the assumptions was that the one of the teachers could have not taught any class. Therefore the possible range starts from 0. Why are we assuming this?
A: We can't assume this. The question tells us that "each of the teachers taught AT LEAST 1, but not more than 3, of the classes," so it can't be the case that one of the teachers taught zero classes.

### Hi Brent, thanks for that. It

Hi Brent, thanks for that. It did say that each teacher taught at least one class, therefore why is the option starting with 0 correct for the least number of teachers?

### The zeros in the answer

The zeros in the answer choices have nothing to do with teachers who TAUGHT ZERO CLASSES.

The question asks, "If the number of teachers who taught 3 classes is n, then the least and greatest possible values of n, respectively, are
A) 0 and 13
B) 0 and 14
C) 1 and 10
D) 1 and 9
E) 2 and 8"

So the zeros in answer choices A and B represent the least possible number of teachers who TAUGHT THREE CLASSES.

Does that help?

### Yes, it surely does. Thanks

Yes, it surely does. Thanks Brent!

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### Hi Brent, I did this question

https://gmatclub.com/forum/donovan-and-michael-are-racing-around-a-circular-400-meter-track-if-d-193270.html

Hi Brent, I did this question in a very weird way:

400/45 = (400-x)/40, get x = 400/9, so I chose answer 9