Word Problem 5

ocgirl83

New member
The excess lifetime cancer risk R is a measure of the likelihood that an individual will develop cancer from a particular pollutant. For example if R=.01, then a person has a 1% increased chance of developing cancer during a lifetime.(this would translate into 1 case of cancer for every 100 people during an average lifetime.) The value of R for formaldehyde, a highly toxic indoor air pollutant, can be calculated using the linear model R=kd, where k is a constant and d is the daily dose in parts per million. The constand k for formaldehyde can be calculated using the formula
k=.132B/W
Where B is the total number of cubic meters of air a person breathes in one day and W is a persons weght in kilograms.
A) find k for a person who breathes in 20m^3 of air per day and weighs 75kg.
B) Mobile homes in Minnesota were found to have a mean daily dose d of .42 part per million. Calculate R uising the value of k found in part (a).
C) for every 5000 people, how many cases of cancer could be expected each year from these levels of formaldehyde? Assume an average life expectancy of 72 years.

stapel

Super Moderator
Staff member
What have you tried? How far have you gotten?

Eliz.

ocgirl83

New member
I've tried to figure all the equations but can't seem to get any of the right answers.

stapel

Super Moderator
Staff member
"Figure" what equation? In (A), they gave you the equation and the values for the variables. All you have to do is plug them in and simplify.

Eliz.

G

Guest

Guest
How much help to give?

I'm new to these forums, so please forgive me if I'm giving too much information. Also, my answers could be wrong. For part A, they want you to solve for k in the equation k=.132B/W. They give you the values for B and W. As Eliz. said, you just need to plug those numbers in to solve it.

So your equation becomes:

k = (.132 * 2.64m^3) / 75kg

Just plug that into a calculator and you get 2.64m^3 / 75kg
Finally you get .0352 cubic meters per kg as the value of k.

For part B, they want you to plug the k value into the R = kd equation, and they give you the value for d.

Again, you just need to plug those numbers in to solve it.

R = .0352 m3/kg * .42 ppm

R = 0.0148 excess lifetime cancer risk

Part C is the most difficult, and I may be missing something.

I took the excess lifetime cancer risk (R)
Figured it out for 5000 people:
1.48% of 5000 = 0.0148 * 5000 = 74
Which should yield the number of people that will die of cancer over a standard lifetime from the group chosen.
Since they gave the standard lifetime as 72, I divided 72 into 74 and got 1.027777 or 1.03 people who would die each year.

-AK