Question

One year, Super Bowl commercial time sold for $4.5 million for 30 seconds of air time.

Answer 1

Yes, for the first question you correct; at a rate of [tex] \frac{4.5mil}{30sec} [tex], one second of airtime would cost $150,000.

For the second, no you wouldn't be able to get 20 minutes of airtime with $3 million.
Let's set up the equation;
[tex] \frac{3mil}{xsec} = \frac{150000dollars}{1sec} \\
3mil*1=150000*x \\
x = \frac{3mil}{150000} = 20 sec [tex]
So at a rate of $150,000 per second, $3 million gets you 20 seconds of airtime.