i dont get this.....?

Question

i dont understand proprtions.... like heres an example

a teacher has 54 research papers to read. she can read three of them in 40 minutes. how long will it take her to read all of the papers at the same rate.

can anyone explain how to do them??

Answer 1

just figure out how many "groups" of 3 papers each are in the stack:

54/3 = 18

each group takes 40 minutes, so the total time is:

18*40 = 720 minutes, or 12 hours.

Answer 2

Divide 40 by 3. If she can read 3 papers in 40 minutes, she can read one paper in 13.33 (40/3) minutes. Multiply 40/3 by 54. This comes to 720 minutes, or 12 hours, the total time it takes to read all 54 research papers.

Answer 3

We know the teacher reads 3 papers in 40 minutes. We can write 3 papers per 40 minutes as (3 papers) / (40 minutes). This gives us our initial ratio.

Now we want to know how long it will take the professor to read 54 papers, thus we want to find x for (54 papers)/(x minutes).

Seting these two ratios equal to each other, we get:
3/40=54/x

Solving for x, we get:
x*3/40=54
x=54*40/3
x=720

So, it would take her 720 minutes (or 12 hours) to read 54 papers.

We can check our answer:
We know 54/3 = 18. So, since there are 18 times more papers, it should take her about 18 times longer to read them.
40*18=720.

I hope this helps. Please give more detail to which part of proportions you do not understand if this doesn't help. Good luck. :-)

Answer 4

She can read 3 in 40 min
=> 1 in 40/3 min
=> 54 in 54 * 40/3 min
=> 720 min or 12 hour

Answer 5

It takes 40 minutes to read 3 papers. Divide 40 by 3 to get 13.33. It takes approximately 13 minutes to read each paper. There are 54 papers so you can multiply 54 by 13.33 to get 719.82 minutes, which = ~ 12 hours.

be right back with better answer

Answer 6

Sure; it's all about unit cancellation.

(54 papers) divided by (3 papers / 40 minutes)

But dividing fractions is the same as multiplying the reciprocal.

(54 papers) times (40 minutes / 3 papers)

The "Papers" unit cancels out, leaving us with

(54)(40 minutes) / 3 = 720 minutes

Answer 7

-Teacher reads 3 papers per 40minutes
-There are 54 papers

54 divide by 3 papers will give you 18 piles or stacks of 3. You then simply multiply 40mins for each stack or pile

54/3 = 18
18 x 40 = 720minutes

Answer 8

I always need to rewrite the info like this:
3----->40
54---->?
With this format you always multiply numbers that are diagonal to eachother and divide by the remaining number. So in this case (54x40)/3
Any proportion problem you have can be solved this way, only the position of the '?' changes according to the info you're given..Also you can check if your answer is correct: If it takes her 40mins just to read 3 then it must take her much longer to read 54..Hope this helps!

Answer 9

well if theres 3 in 40...3/40min(13.33..min per paper), then i would just simply multiply that by 54 to get 720min.

Answer 10

her speed = 3 papers / (2/3 hours) = 4.5 papers/hour

time = 54 papers / 4.5 papers/hour = 12 hours