# Functions - Problem Solving

• Mar 24th 2010, 04:51 PM
Jiyongie
Functions - Problem Solving
I don't understand my teacher at all! Or maybe it's just me doing something wrong..?

1) Shannon's mother brings her to an indoor playground. The admission costs \$3 plus an additional fee for each half-hour of play. It costs \$6 for Shannon to play for one hour. Graph the relationship.

So I have two equations:

y = 3 + (0.5)(x)(h) ---> x = fee
6 = 3 + (0.5)(x)(2)

What I don't understand is why my teacher wrote:

6 = 3 + 3h

2) An internet provider sets its rates according to the following scheme. It charges \$1.25 to log-on with the service and an additional \$0.25 for every 10 minutes online. Write an equation to represent the total charge, C, in dollars, as a function of time online, h (hours).

This is the same type of question as the first one..
The equation I got:

10 minutes/60 minutes = 1/6
C = 1.25 + (0.25)(1/6)(h)
C = 1.25 + (1/24)(h)

I don't understand why my teacher wrote this:

C = 3.5h + 1.25

• Mar 24th 2010, 05:39 PM
bjhopper
Functions-problem solving
Quote:

Originally Posted by Jiyongie
I don't understand my teacher at all! Or maybe it's just me doing something wrong..?

1) Shannon's mother brings her to an indoor playground. The admission costs \$3 plus an additional fee for each half-hour of play. It costs \$6 for Shannon to play for one hour. Graph the relationship.

So I have two equations:

y = 3 + (0.5)(x)(h) ---> x = fee
6 = 3 + (0.5)(x)(2)

What I don't understand is why my teacher wrote:

6 = 3 + 3h

2) An internet provider sets its rates according to the following scheme. It charges \$1.25 to log-on with the service and an additional \$0.25 for every 10 minutes online. Write an equation to represent the total charge, C, in dollars, as a function of time online, h (hours).

This is the same type of question as the first one..
The equation I got:

10 minutes/60 minutes = 1/6
C = 1.25 + (0.25)(1/6)(h)
C = 1.25 + (1/24)(h)

I don't understand why my teacher wrote this:

C = 3.5h + 1.25

Your teacher wrote an equation for Shannon.You have to make it general and graph cost versus hours played .
The second is similar but be careful
• Mar 24th 2010, 06:10 PM
Jiyongie
For the first question though, why did he leave "h" there? We know Shannon played for 1 hour, which is two half-hours...

Second question - how do I get 3.5 as the coefficient!?
• Mar 25th 2010, 06:38 AM
bjhopper
Quote:

Originally Posted by Jiyongie
I don't understand my teacher at all! Or maybe it's just me doing something wrong..?

1) Shannon's mother brings her to an indoor playground. The admission costs \$3 plus an additional fee for each half-hour of play. It costs \$6 for Shannon to play for one hour. Graph the relationship.

So I have two equations:

y = 3 + (0.5)(x)(h) ---> x = fee
6 = 3 + (0.5)(x)(2)

What I don't understand is why my teacher wrote:

6 = 3 + 3h

2) An internet provider sets its rates according to the following scheme. It charges \$1.25 to log-on with the service and an additional \$0.25 for every 10 minutes online. Write an equation to represent the total charge, C, in dollars, as a function of time online, h (hours).

This is the same type of question as the first one..
The equation I got:

10 minutes/60 minutes = 1/6
C = 1.25 + (0.25)(1/6)(h)
C = 1.25 + (1/24)(h)

I don't understand why my teacher wrote this:

C = 3.5h + 1.25

Shannon's equation defined the hourly rate as \$3 per hour so C=3 +3 h.
The second is similar.Do it the same way and assume the teacher throws curves or made a mistake

bjh
• Mar 25th 2010, 07:30 AM
BabyMilo
Quote:

Originally Posted by Jiyongie
I don't understand my teacher at all! Or maybe it's just me doing something wrong..?

1) Shannon's mother brings her to an indoor playground. The admission costs \$3 plus an additional fee for each half-hour of play. It costs \$6 for Shannon to play for one hour. Graph the relationship.

So I have two equations:

y = 3 + (0.5)(x)(h) ---> x = fee
6 = 3 + (0.5)(x)(2)

What I don't understand is why my teacher wrote:

6 = 3 + 3h

what u did is right. but we want h to be a variable and x to be a constant.

since the addition charge or cost is fixed (ie not a percentage cost).

so you rearrange to find x.

6 = 3 + (0.5)(x)(2)
3=1x
x=3

so the overall equation = y=3+3h
where y varies with h.

hope this helps.