# T-Shirts

• Dec 28th 2008, 08:30 AM
magentarita
T-Shirts
To print T-shirts includes \$50 for the design and \$4 per shirt. Express the cost of printing the T-shirts as a function of the number of T-shirts printed and then find the cost for printing 500 T-shirts.

MY WORK:

My linear function model is:

T = \$4P + \$50...Is this correct?

To print 500 T-shirts will cost:

500 = 4P + 500

500 - 50 = 4P

450 = 4P

450/4 = P

\$112.50 = P

Let P = price

Let T = T-shirts

Does this make sense? Is this right?
• Dec 28th 2008, 09:26 AM
masters
Quote:

Originally Posted by magentarita
To print T-shirts includes \$50 for the design and \$4 per shirt. Express the cost of printing the T-shirts as a function of the number of T-shirts printed and then find the cost for printing 500 T-shirts.

MY WORK:

My linear function model is:

T = \$4P + \$50...Is this correct?

To print 500 T-shirts will cost:

500 = 4P + 500

500 - 50 = 4P

450 = 4P

450/4 = P

\$112.50 = P

Let P = price

Let T = T-shirts

Does this make sense? Is this right?

Hello Magentarita,

Your function is correct, but you lost me after that. I'll write the function in a little different way. Let t = number of T-shirts. Then

$f(t)=4t+50$

Now, all you need to do is find f(500)

$f(500)=4(500)+50$
• Dec 29th 2008, 03:59 AM
HallsofIvy
Quote:

Originally Posted by magentarita
To print T-shirts includes \$50 for the design and \$4 per shirt. Express the cost of printing the T-shirts as a function of the number of T-shirts printed and then find the cost for printing 500 T-shirts.

MY WORK:

My linear function model is:

T = \$4P + \$50...Is this correct?

Not until after you have said that "P" is the number of T-shirts and "P" is the cost of printing! Which seems peculiar to me!

Quote:

To print 500 T-shirts will cost:

500 = 4P + 500
Oops! You were using "T" to mean the number of T-shirts and "P" to mean the cost of printing! That makes more sense but then the formula is wrong.
Look at an easy case. If you were to print only one T-shirt, it would cost \$50 for the design and 4 dollars for the shirt, a total of \$54, not "1= 4P+ 500".

That's what confused masters.

Quote:

500 - 50 = 4P

450 = 4P

450/4 = P

\$112.50 = P

Let P = price

Let T = T-shirts

Does this make sense? Is this right?
• Dec 29th 2008, 10:20 PM
magentarita
ok.........
Quote:

Originally Posted by masters
Hello Magentarita,

Your function is correct, but you lost me after that. I'll write the function in a little different way. Let t = number of T-shirts. Then

$f(t)=4t+50$

Now, all you need to do is find f(500)

$f(500)=4(500)+50$

I see what I did wrong. Thanks.
• Dec 29th 2008, 10:20 PM
magentarita
ok........
Quote:

Originally Posted by HallsofIvy
Not until after you have said that "P" is the number of T-shirts and "P" is the cost of printing! Which seems peculiar to me!

Oops! You were using "T" to mean the number of T-shirts and "P" to mean the cost of printing! That makes more sense but then the formula is wrong.
Look at an easy case. If you were to print only one T-shirt, it would cost \$50 for the design and 4 dollars for the shirt, a total of \$54, not "1= 4P+ 500".

That's what confused masters.

Thank you for clearing things up for me.
• Dec 30th 2008, 04:27 AM
HallsofIvy
That is why, by the way, when you are converting word problems into equations, it is a very good idea to write, separately, exactly what each letter you use MEANS.
• Jan 3rd 2009, 08:52 AM
magentarita
my biggest problem
Quote:

Originally Posted by HallsofIvy
That is why, by the way, when you are converting word problems into equations, it is a very good idea to write, separately, exactly what each letter you use MEANS.

This is the biggest problem I have in math--->converting word problems to equations. Students in general have a real hard time with word problems.

As you know, they are not clearly stated. Most of the time, knowing which operation or combination of math operations to apply to find the answer is the main struggle for students.