Hi, Jay.

I've also noticed that. For me, work well go further into the hints. They solved the problems step by step. After read a few detailed solutions in the hints section, I get ready to handle the exercises with any hint at all.

They do some conversions in the hints that they don't explain where it came from and such. If just jumps right past it.. also I'm not looking to *solve* the problem, but to understand the math behind it fluently, and to do that the missing videos are probably key

I believe what I need to know, and what is missing, is the ability to know when to flip a fraction.

For instance if 45 mins = 3/8 (#people/#walls) when reducing the fraction to 1/1 (1person/1wall) what fraction(or inversion of a fraction) do I use?

Such as 3/8 * 1/8? And if so why? The videos just aren't there to explain why... And how.. so I know what I'm suppose to do, but I don't know WHY I'm suppose to do it.. which kinda defeats the purpose of trying to learn the fundamentals to me...

Please either show me a resource I'm not seeing, or please fix the stuck videos!

If 3 people paint 8 walls in 45 minutes, how many minutes takes to 1 person paint 1 wall?

So, lets do it in an instructive way:

45 minutes = 3/8 people per walls, right?

In order to transform 3/8 in 1/1, you have to divide 3/8 by 3/8, which means multiply 3/8 by 8/3.

So, multiplying both sides of the equation by 8/3 we get

45 x 8/3 minutes = 3/8 x 8/3 people per walls

=> 15 x 8 minutes = 1/1 person per wall

=> 120 minutes = 1 person per wall.

So, 1 person paint 1 wall in 120 minutes.

I hope you find that really instructive.

Bests,

Leo Maykell.

Yea that helps, why the videos don't have that one piece of info is beyond me!

In one of the videos they break it down step by step, so instead of *8/3 they do *1/3 and then *8/1? I think?

It's very confusing doing it the way I'm saying, but it's also the only way I can slow walk what im suppose to do..

Is there a video or anything you know other than Khan academy that has a walk through of this?

Yes, Jay, unfortunately the videos are not helpful on this... I agree with you 100%

New question same problem.

46 mins = 10/3 (people/wall)

Break it down to 1 person a wall, and then show how much time it'll take 4 people to do 6 walls.

I did the math and have it down to 460/3(mins) or 153-1/3 mins = 1/1
But now I need to go back up!
Can you show a step by step of the multiplication of the fractions and their inversions and why?

Do I times both side by 4/6?

Thank you for the answers. I had the exact same problem. These rate questions threw me for a loop.