SOLUTION: This word problem has got me stumped. Any help you can provide would be appreciated. The percent of deaths caused by smoking is modeled by the rational funtion defined by: P(X)

Question 28570: This word problem has got me stumped. Any help you can provide would be appreciated.
The percent of deaths caused by smoking is modeled by the rational funtion defined by: P(X)=X-1/X
where x is the number of times a smoker is more likely to die of lung cancer than a nonsmoker. x is equal to 10.
Please help me find:
a. p(x) if x is 10
b. For what values of x is p(x) = 80%
c. Can the incidence rate equal zero, explain.
I know this is asking alot, but I have been over this several times, and can't even figure out where to begin.
Thanks!
Lisa
Answer by venugopalramana(3286) (Show Source): You can put this solution on YOUR website!
This word problem has got me stumped. Any help you can provide would be appreciated.
The percent of deaths caused by smoking is modeled by the rational funtion defined by: P(X)=X-1/X...HOPE YOU ARE CORRECT IN TYPING..AS TYPED THIS MEANS
...X-(1/X)....IF BRACKETS ARE NOT PUT PROPERLY IT COULD MEAN (X-1)/X.I AM TAKING IT AS X-(1/X)
where x is the number of times a smoker is more likely to die of lung cancer than a nonsmoker. x is equal to 10.
Please help me find:
a. p(x) if x is 10
JUST PUT 10 IN PLACE OF X IN THE GIVEN FUNCTION OF P(X) TO GET THE ANSWER.
P(X)=X-1/X =10-1/10=(10*10-1)/10 = (100-1)/10 =99/10

b. For what values of x is p(x) = 80%
HERE PUT P9x0 IN THE GIVEN FUNCTION AND FIND X
P(X)=X-1/X =80% = 80/100=8/10=4/5
(X*X-1)/X=4/5..CROSS MULTIPLYING..
5X^2-5=4X
5X^2-4X-5=0
THE ANSWER IS OBTAINED USING QUADRATIC EQUATION FORMULA

X={4+SQRT(116)}/10...OR....={4-SQRT(116)}/10...

c. Can the incidence rate equal zero, explain.
YOU MEAN CAN P(X) BE ZERO?? IS THE QUESTION..
P(X)=X-1/X =0%
(X*X-1)/X=0..CROSS MULTIPLYING..
X^2-1=0
X^2 = 1
X=1 OR -1...SO MATHEMATICALLY IT IS POSSIBLE .BUT THE FEASIBILITY OF X TAKING THAT VALUE IN REALITY SAY -1 IS IMPOSSIBLE AND EVEN +1 IS DEBATABLE.

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