SOLUTION: I don't really know what category to put this is because our teacher doesnt explain anything. No one in the class knows how to do this problem and I'm on the verge of failing so...

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Question 289888: I don't really know what category to put this is because our teacher doesnt explain anything. No one in the class knows how to do this problem and I'm on the verge of failing so...yeah.
1. The pressure exerted by Earth's atmosphere at sea level is about 14.7 pounds per square inch. For every mile above sea level, the pressure decreases by about 18%.
a. Write an equation for the pressure y (in pounds/sq. inch) at height x (in miles) above sea level.
b. Use a graph of the function from Exercise 1 to determine at what height the atmospheric pressure is half of what it is at sea level.
c. Find out how many more miles above the height from Exercise 2 the atmospheric pressure will be halved again.
I tried using the y=ab^x formula since that's what we were working with at the time, but I don't know how to solve it that way since there's not enough data to do the subtracting of exponents? I started it like this
y=14.7(.18)^x
y=2.646^x
and put pounds as independent (x) and pressure as dependent (y) but i don't think that's right since I have no idea where to go with this after that. Help would be amazing.
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
How about taking some responsibility for your troubles?
Do you have a book? Is everyone failing?
Maybe you hang around with the wrong crowd!

The next steps in the problem is to graph it.
You did a now do b and c
a. Write an equation for the pressure y (in pounds/sq. inch) at height x (in miles) above sea level.
b. Use a graph of the function from Exercise 1 to determine at what height the atmospheric pressure is half of what it is at sea level.
c. Find out how many more miles above the height from Exercise 2 the atmospheric pressure will be halved again.
BTW is the equation (ab)^x or just a*(b^x)
You treated it as (ab)^x
y=(14.7)*(.18)^x
get a value for x first then raise .18 to that power
What is the pressure at height 0 : 14.7
When is the pressure 7.35
7.35=14.7*.18^x
.5=.18^x
x=abt .4
4/10 of a mile