Answer:
Her usual driving speed is 38 miles per hour.
Step-by-step explanation:
We know that:

In which s is the speed, in miles per hour, d is the distance, in miles, and t is the time, in hours.
We have that:
At speed s, she takes two hours to drive. So


However, on one particular trip, after 40% of the drive, she had to reduce her speed by 30 miles per hour, driving at this slower speed for the rest of the trip. This particular trip took her 228 minutes.
228 minutes is 3.8 hours. So

So




Her usual driving speed is 38 miles per hour.
Just by comparing the plots of f(x) and g(x), it's clear that g(x) is just some positive scalar multiple of f(x), so that for some constant k, we have
g(x) = k • f(x) = kx² = (√k x)²
The plot of the transformed function g(x) = (√k x)² passes through the point (1, 4), which means
g(1) = (√k • 1)² = 4
and it follows that k = 4. So g(x) = 4x² = (2x)² and B is the correct choice.