Math Gr12 Advanced Functions
posted by Billy Bob on .
I am stuck on this one part of this question:
The function S(d)=93(logd)+65 relates the speed of the wind S, in miles per hours, near the centre of a tornado to the distance that the tornado travels,d,in miles. If a tornado has sustained winds of about 250 mph, estimate the distance it can travel.
I do this :
250= 93logd +65
185/93= logd
logd= 0.989247312
I don't know what to do after that because I cannot divide anything by log. Or is there some other way I should be doing this?

You have to take the inverse of log, that is ...
what number d you you need, so that log d = .989...
BTW, I got log d = 1.9892....
hope yours was just a typo.
On most calculators, use the 2ndF key
on mine, I would press the following:
2ndF
log
1.98924..
=
to get 97.5545
Without having to reenter the 1.98...
Here is the sequence of my keystrokes
250

65
=
รท
93
=
2ndF
log
=
to get the 97.5545