A, B, and D worked out, but when I try to do C I run into a problem.
I use the formula:
f(t)=90-15log(6+1)
For an answer I get:
90+log(1/474561509943)
Im pretty sure im doing something wrong because the other answers were more like 90 and 50
A, B, and D worked out, but when I try to do C I run into a problem.
I use the formula:
f(t)=90-15log(6+1)
For an answer I get:
90+log(1/474561509943)
Im pretty sure im doing something wrong because the other answers were more like 90 and 50
When I did 90-15log(7) I got an answer of 77.3 (3sf). Are you sure you put it in your calculator correctly?
Google's calculation
I got an answer of 9 (I assume t is in months)
$\displaystyle 75 = 90 - 15log_{10}(t+1)$
$\displaystyle 75-90 = -15log_{10}(t+1)$
$\displaystyle -15 = -15log_{10}(t+1)$
-15 will cancel to give us $\displaystyle log_{10}(t+1) = 1$
$\displaystyle t+1 = 10^1 = 10$
$\displaystyle t=9$