applications 11 exponential and logarithmic equations 1 finance sung l

Question

Applications 11: Exponential and Logarithmic Equations
1. Finance
Sung Lee invests $5,000 at age 18. He hopes the investments will be worth
$10,000 when he turns 25. If the interest is compounded continuously,
approximately what rate of growth will he need to achieve his goal? Is that a
reasonable expectation? Why or why not?
2. Sound
The formula for measuring sound intensity in decibels D is defined by the
1D = 10log(+),
where I is the intensity of the sound, in watts per
-12 W
square meter, and I = 10
is the lowest level of sound that the average
person can hear. What is the intensity of a hair dryer that makes a sound of
90dB?
equation
m