Piecewise Functions: modelling pediatric medication dosages

[raerae1974]

I need to do an Algebra assignment and I am so lost. I need to pick a childrens medication and find the directions for administration. Noting the child's weight or age and the corresponding dosage. The drug should have a minimum of 4 weight or age intervals.

1) The directions say that I am to create a table for the data where x=weight interval of child(or age interval of the child) y=corresponding drug dosage
2)Then I need to graph the information on graph paper. I should have a piecewise function after doing this.
3) Then name the domain for the function.
4) Then name the range for the function.

5)Then create a table for the same data, however let x=minimum weight in the weight interval (or minimum age in the age interval) y=corresponding drug dosage.
6)Create a scatter plot for the data.
7)Name the domain.
8) Name the range.
9) Create a line graph for the data.
10) Find a linear equation for the line using y-y1=m(x-x1).
11) Use model from question 10 to determine symbolically, the amount of medication that should be administered to a child weighing 40 pounds or age 3.5 years.

**Any help is greatly appreciated!!!****

 

[Deleted member 4993]

Re: Piecewise Functions

I need to do an Algebra assignment and I am so lost. I need to pick a childrens medication and find the directions for administration. Noting the child's weight or age and the corresponding dosage. The drug should have a minimum of 4 weight or age intervals.

1) The directions say that I am to create a table for the data where x=weight interval of child(or age interval of the child) y=corresponding drug dosage
2)Then I need to graph the information on graph paper. I should have a piecewise function after doing this.
3) Then name the domain for the function.
4) Then name the range for the function.

5)Then create a table for the same data, however let x=minimum weight in the weight interval (or minimum age in the age interval) y=corresponding drug dosage.
6)Create a scatter plot for the data.
7)Name the domain.
8) Name the range.
9) Create a line graph for the data.
10) Find a linear equation for the line using y-y1=m(x-x1).
11) Use model from question 10 to determine symbolically, the amount of medication that should be administered to a child weighing 40 pounds or age 3.5 years.

**Any help is greatly appreciated!!!****

Please share your work with us, indicating exactly where you are stuck - so that we know where to begin to help you

 

[raerae1974]

Re: Piecewise Functions

I am stuck from the very beginning, have no idea on where to start.

 

[mmm4444bot]

I am stuck from the very beginning, have no idea on where to start.

You could start by following the instructions.

… pick a childrens medication and find the directions for administration …

It took me about 90 seconds using Google to find the charts at the following link.

http://www.gardencitypediatrics.com/medicationdosages.html

Next, do you know how to graph points using (x, y) coordinates?

 

[raerae1974]

Ok--i have the 4 weights now I am not sure how to create a table for the data where x=weight interval of child and y=corresponding drug dosage. Does this just mean write it and then try to graph it?

 

[mmm4444bot]

… I am not sure how to create a table … Does this just mean write it …

Yes, write the table as two columns. One column for the weight intervals, and another column next to it for the corresponding dosage amounts.

I don't know which data you've chosen, but here's an example for Benadryl.

Pick symbols to represent the child's weight and the medication dose. I'll choose W and D.

W = child's weight in pounds

D = medication dose in teaspoons

         W                   D
---------------------------------
    11 <= W < 16           0.50
    16 <= W < 22           0.75
    22 <= W < 33           1.00
    33 <= W < 44           1.50
    44 <= W < 66           2.00
    66 <= W < 88           3.00

So, for example, to find the dose for a child who weighs 40 pounds, we look for the interval for W that contains the value 40, and then we read off the corresponding value of D as one and one-half teaspoons.

The graph of all of this data will look like a step-function. Since the dose is constant within each interval, the graph in each interval will be a horizontal line segment.

Since these are half-open intervals, there is a solid circle at the left end of each segment and an open circle at the right end, to indicate which endpoint is included and which one is not.

The horizontal axis is called the W-axis, and the vertical axis is called the D-axis.

 

[raerae1974]

ok--i think that I got that. Now I am trying to name the domain and the range for the function.

 

[mmm4444bot]

ok--i think that I got that. Now I am trying to name the domain and the range for the function.

I do not think that you've "got" much at all, other than what I've already done for you.

I'm not doing any more of this assignment for you, until you show me that you're capable of some independent thinking.

In other words, if you want more help with this exercise from me, then you need to show your work and explain your reasoning.

 

[raerae1974]

ok-thanks for the help--i never asked anyone to do the assignment for me, just asked for help. Never done this type of problems before and never used this site so I am not even sure how to draw graphs and things like that on here. I have my information on paper just not able to show anyone. I am really struggling with this but I do not want anyone to think that I want them to do the work for me, how will that ever help me on test and things like that if I do not even know how to do the work. So to prevent folks from thinking that they are doing the work, I will just not ask for any more help on here. Thanks.

 

[mmm4444bot]

… to prevent folks from thinking that they are doing the work, I will just not ask for any more help on here.

Since it's your decision, I will support any reasonable approach toward getting help that you desire. Even one as radical as this one.

Cheers,

~ Mark