Poll: Math question

[diamarie]

So, like I dunno if this is fit for this here forum.. But let's try.
Ask me to differentiate, integrate, and I'll get it out. But for the life of me I can't figure this out.
It's a SATs question.

"John can shovel a driveway in 50 mins. If Mary can shovel the same driveway in 20mins, how long will it take them, to the nearest minute, to shovel the driveway if they work 2gether"

The answers are 12, 13, 14, 17 or 18


Anyone have any ideas?

 

[On the Path]

The best I could come up with is that it takes John 2.5 minutes to do what mary does in one minute

 

[On the Path]

based on a poll of my friends, here is what they said:

"snowball fight"
"they find something else to do"
"35 minutes"

 

[Jesuslovesu]

Ok here is my answer... I thought about it and well I come up with 13 this is how I come to this conclusion..If there is the 1.5 time difference i then took mary's time and divided it by 1.5 that equals 13.3333333333333 so 13 is my answer so you know I am terrible in math so there is a REALLY good chance I am wrong... I would like to know the right answer though.

 

[On the Path]

Johnny can do 1/50 of the driveway in a minute, and she can do 1/20 in a minute.

If they work for x minutes together, they will get x/50 + x/20 of the driveway done.
We want that to be the whole driveway, so we want x/50 + x/20 = 1, Multiply by 100 (the least common denominator), and we get

2x + 5x = 100
7x = 100
x = 100/7 = 14.2857... minutes.


:shade:

 

[Faithful Son]

I'm extremely bad with maths, so my answer was based on instinct, hehehe

I said 18 minutes, if John takes 50 and Mary 20, they should do it togther in 18, I am sooooo bad in maths

 

[diamarie]

Well, being supposedly mathematically inclined, I got 14 2/7 ... Don't ask how, cuz it gave me a headache to explain the first time.. And some of it doesn't make sense.
So I say 14 is the answer

 

[SmileBig]

well worked A can clear the drive in 50 minutes and worker B can do it in 20 minutes so se need to put distance to the drive to help

if the drive is 100 feet then worker A can do 20 feet every 10 minutes ( a ratio of 2 feet a minute and worker B can to 50 feet every 10 minutes (a ratio of 5 feet a minute).

Therefore in 14 minutes worker A can do 28 feet and B can do 70 feet a total of 98 feet.....

I confer with my colleague, just over 14 minutes

I am scared as I just confused myself ROFL

 

[diamarie]

Praise God. I think it's the right answer

 

[baruch]

Hi, I worked it out this way:
If the drive was 50 feet, John would shovel 1 foot a minute while Mary would shovel 2.5 feet a minute. Both working together, they would shovel 3.5 feet per minute. 50 divided by 3.5 = 14.285714 minutes.

3nails+1cross=4given

 

[trulyblezzed]

I'm getting dizzy just thinking about all these numbers sorry :embarasse

 

[Soundman]

I am suppose to be gd at Maths and agree with the 7x=100 solution but i did it as after 10 minute Lady does 1/2 or 0.5 with the lazy bloke having done additional 1/5 or 0.2 . So 10 minutes for 0.7 to be done. so each additional minute 0.07 would be done so 0.3 divide 0.07 give 4.288 so 4 minutes more giving total 14 minutes.

 

[Ronda]

ok Mary can do 3/4 of drive in 15 min- John can do 1/4 in 12.5 min his leftover helps her get done just a bit sooner so it is the 14