Math Help

Working on infinite algebra word problems and need some help. Nights referred me to the second solution here, but it's not really clear to me, like it's missing a step.

Working alone, Ryan can dig a 10 ft. by 10 ft. hole in five hours. Castel can dig the same hole in six hours. How long would it take them if they worked together?

Figuring that one out will help me with the others. Same algebra, just different numbers.

 

I ain't digging shit

 

Do your own homework. Builds character.

 

10+10+5+6=101056 hours
the lesson here is dont work with people

 

I finished up math in college a few semesters back and now I can't look at these and understand them, but after seeing that link I get what the problem is asking and how it's solved.

Basically you have X being the number you're looking for, and it's essentially just a simple problem...trying to think of the words of them, but I can't. It's like those problems 25x + 5 = 20X - 10 and finding out what X is and if they're equal. Note that those were random numbers I just put in there though. Either way, you have X being what you're looking for, and so you figure out what the two of them can do together, so you're multipying them. The 1/5 and 1/6 is what each guy can do, 1 hole per 5/6 hours, and you multiply them, so you get 6 + 5. And of course, what you do to one side you do to the other. After that you end up with the 11x = 30, and just get X by itself and get you answer, with the full number being hours and decimals being minutes. You can multiply 60 by 0.7273, which you end up with 43.638, and you just round.

Hope that cleared it up or made it more understandable.

 

Sort of, but I just figured out all I have to do is one over the number of hours on each side (e.g., 1/10 and 1/7) and then find common denominators by multiplying and then adding. (For example, Shawna can pour a large concrete driveway in six hours. Dan can pour the same driveway in seven hours. Find how long it would take them if they worked together.)

But now it's changed a little and I'm stuck again.

Working together, Paul and Daniel can pick forty bushels of apples in 4.95 hours. Had he done it alone it would have taken Daniel 9 hours. Find how long it would take Paul to do it alone.

Do I just do 1/4.95 and 1/9? The .95 seems like it will make it complicated, though.

 

decimals cant be in fractions

 

So what do I do when it's not a solid hour? I'm trying to get some studying in before my placement test tomorrow.

 

i have no idea

 

Believe in yourself or do copious amounts of drugs.

 

im not a smart person i dont know math

 

I haven't believed in myself in years.

 

Do you need a hug?

 

But you're....a number[DOUBLEPOST=1424236915][/DOUBLEPOST]

The copious amount of drugs is doing me just fine. Thank you, though.

 

Everyone always says that....

 

But seriously, help! :x

 

If you have a word problem where you need to combine things and you're having trouble setting it up, I was always taught to make a table.

This is essentially a combined work problem in reverse since you are given the combined work at the beginning and expected to find the individual work. You are given Daniel's individual work (40 bushels in 9 hours), but not Paul's.

So how do you solve for just Paul's (work)speed (or time really since you are given one component of this), given the speed of both of them together and Daniel's individual speed/rate? That's essentially what the question is asking. The most important, and imo trickiest part of a word problem is to understand what information is being asked for, aka what information your variable is. In this case it is the time Paul takes to pick 40 bushels of apples by himself. This is your x!

Setting up the table, we have Paul, Daniel, and the two together as our columns or rows, and the number of bushels & hours each takes as the other. We're given times, except Paul's, and we know that it will be 40 bushels in each case.

If you understand that the rate will be bushels/hour, it becomes easy from there to set up the problem:

40/x + 40/9 = 40/4.95

The unknown rate of Paul plus the rate of Daniel is the rate of the two combined.

Solve for x and you should get roughly 11 hours.

 

That's the answer (11), but I'm getting 0.12 , so I'm doing something wrong. And when I use the calculator I get 0.12375.

 

You are dividing backwards. x being time, It's 40/x, not x/40.