Calculation using 3 quantities: Shoveling snow to earn money

[zak100]

Summary:: Hi,
I am trying to solve the following:
A person shovels driveways to earn money. She can shovel 12 driveways in 6 hours. She earns 18$ for each driveway.The person needs 360$ to buy a computer. How may hours does the person need to work?

I am using unity method :
18$----6 hour
1 $----6/18
360$...6/18 * 360
= 120 hours

Some body please guide me.

Zulfi.

 

[PeroK]

Summary:: Hi,
I am trying to solve the following:
A person shovels driveways to earn money. She can shovel 12 driveways in 6 hours. She earns 18$ for each driveway.The person needs 360$ to buy a computer. How may hours does the person need to work?

I am using unity method :
18$----6 hour
1 $----6/18
360$...6/18 * 360
= 120 hours

Some body please guide me.

Zulfi.

That seems like a lot of work. 120 hours for $360 is only $3 per hour.

 

[zak100]

What is the correct solution?

 

[Mark44]

Summary:: Hi,
I am trying to solve the following:
A person shovels driveways to earn money. She can shovel 12 driveways in 6 hours. She earns 18$ for each driveway.The person needs 360$ to buy a computer. How may hours does the person need to work?

I am using unity method :
18$----6 hour

No, this is wrong.
If she can shovel 12 driveways in 6 hours, how long does it take for her to shovel 1 driveway?

1 $----6/18
360$...6/18 * 360
= 120 hours

No, this is way off.

 

[zak100]

Yes, I know its but do you know the correct one?

Zufi.

 

[Mark44]

Yes, I know its but do you know the correct one?

Yes.

 

[sysprog]

It's not even algebra. It's very basic arithmetic. If you feel lazy bring up the calculator on the machine you're using.

 

[jedishrfu]

Start with $360 and compute how many driveways that is and then it should be clear how long it will take.

 

[zak100]

Hi,

This means that you know the answer.
360/18 = x/12

x = 240 drive ways
I don't know if the above is correct.

Somebody please guide me.

Zulfi.

 

[phyzguy]

Hi,

This means that you know the answer.
360/18 = x/12

x = 240 drive ways
I don't know if the above is correct.

Somebody please guide me.

Zulfi.

It's not correct. Start with step 1 as @jedishrfu suggested. If she earns $18 for each driveway, how many driveways does she have to shovel to earn $360. Can you answer this?

 

[Mark44]

If she can shovel 12 driveways in 6 hours, how long does it take for her to shovel 1 driveway?

If she earns $18 for each driveway, how many driveways does she have to shovel to earn $360. Can you answer this?

Really, this problem is simple enough that you should be able to do it in your head.

 

[Mark44]

x = 240 drive ways

At $18 per driveway, she would earn $4320, enough to buy a dozen computers at $360 each.

Instead of blindly applying a formula that you don't understand, read through this thread. You've been given lots of hints.

 

[hutchphd]

Would someone please use the magic phrase: "put units with each of the three numbers"

The correct answer will have units of hrs/computer. There is only one solution.

 

[zak100]

Hi,

Actually there is a formula for it. I don't know if you guys know the formula.

Zulfi.

 

[jedishrfu]

There's a funny story about formulas and mastery: The students memorize the formulas and conditions under which they apply whereas the master derives the formula but only if he/she needs it.

This model is born out in Introductory Physics classes and once the student gains mastery then Lagrangian and Hamiltonians are used with boundary conditions and those confusing Intro formulas go by the wayside.

 

[zak100]

My friend, this is not physics. I have given you a hint. Please use formula, it would be easier for you because I think your background is physics.

Zulfi.

 

[sysprog]

My friend, this is not physics. I have given you a hint. Please use formula, it would be easier for you because I think your background is physics.

Zulfi.

You're saying something to a senior instructor who is voluntarily and without compensation assisting you in handling a problem that would not be too difficult for you to do without assistance if you would think it through. Many of us immediately see the answer, but we want you to see it, so we don't just tell the answer. The same is true on Physics Forums for problems that are far more difficult.

 

[phyzguy]

My friend, this is not physics. I have given you a hint. Please use formula, it would be easier for you because I think your background is physics.

Zulfi.

You misunderstand. Most of us on this thread can immediately see the answer to your problem in our heads with very little thought. I'm frankly amazed that the answer was not obvious to you and that you are still posting about it. Memorizing a formula for every possible problem you will face in life is not the way to learn. You need to be able to think about what the problem is asking and what you need to do to find the answer without needing a formula.

Can I ask what level of schooling you are in where you received this problem?

 

[sysprog]

@zak100 Is there possibly a language interpretation issue?

 

[zak100]

Hi,
Excuse me, I am sorry, your mentor was insulting me:

The students memorize the formulas and condition under which they apply whereas the master derives the formula but only if he/she needs it.

Zulfi.

 

[sysprog]

Hi,
Excuse me, I am sorry, your mentor was insulting me:Zulfi.

No; he was not insulting you; not at all was anyone insulting you.

 

[phyzguy]

Hi,
Excuse me, I am sorry, your mentor was insulting me:
Zulfi.

If you consider @jedishrfu's comment an insult, you have a very thin skin. He was trying to help you learn.

 

[zak100]

You misunderstand. Most of us on this thread can immediately see the answer to your problem in our heads with very little thought. I'm frankly amazed that the answer was not obvious to you and that you are still posting about it. Memorizing a formula for every possible problem you will face in life is not the way to learn. You need to be able to think about what the problem is asking and what you need to do to find the answer without needing a formula.

Can I ask what level of schooling you are in where you received this problem?

I would call it a scapegoat instead of talking about the problem you are talking about the school. Why are you asking private information? This looks like hacking.

Zulfi.

 

[sysprog]

I would call it a scapegoat instead of talking about the problem you are talking about the school. Why are you asking private information? This looks like hacking.

Zulfi.

That looks to me like you might be in need of some adjustment in your personal perspective.

You showed up here asking for advice on something that most of us would consider to be a very easy problem.

Then you apparently got miffed when you were gently and courteously instructed, and were merely asked something that amounted to something like what grade are you in, because the problem you posed is pretty much meant to be solved by young children, or as we in the US and elsewhere say, "child's play".

I think that maybe English isn't your first language, and so maybe there is a difficulty for you in interpreting the problem, and in understanding the responses.

Please don't suppose that anyone here intended to demean, degrade, or insult you.

 

[mfb]

@zak100: If you want to learn something, that's great. Several users here have given useful hints how to approach the (quite simple) problem, and told you what went wrong with your approach. They also offered advice how to avoid similar mistakes in the future.

Meanwhile you are ignoring all that advice, calling it insulting and other things. This isn't the right approach to learn. Not at all. I closed this thread.