Suppose the population of trout in a certain strech of a river is 4000. In about how many years will the population of trout be 700 if the decay rate is 35%? Use the equation 700= (4000)(0.65)^x and round the value of x to the nearest year.
A.5
B.2
C.3
D.4

Question

Suppose the population of trout in a certain strech of a river is 4000. In about how many years will the population of trout be 700 if the decay  rate is 35%? Use the equation 700= (4000)(0.65)^x and round the value of x to the nearest year.
A.5
B.2
C.3
D.4

anonymous · Answer

you can solve directly but since you have answer choices you can check them and see which one gives you 700

anonymous · Answer

not 5 http://www.wolframalpha.com/input/?i=%284000%29%280.65%29^5

anonymous · Answer

not 2 http://www.wolframalpha.com/input/?i=%284000%29%280.65%29^2

anonymous · Answer

not 3 http://www.wolframalpha.com/input/?i=%284000%29%280.65%29^3

anonymous · Answer

got it on the last try http://www.wolframalpha.com/input/?i=%284000%29%280.65%29^4