This has had a few cow orkers scratching their heads
a car drives a mile at 30mph; it then drives another mile.
How fast must it drive the second mile to average 60mph for 2 miles?
To average 60mph for 2 miles, you must complete the 2 miles in 2/60 = 0.033333 hours.
If you have already driven 1 mile at 30 mph, you have already used 1/30 = 0.033333 hours.
You are already out of time.
You have no remaining time.
You would need to drive infinitely fast for the remaining mile.
You are DNF.