Answer:
4 stations
Step-by-step explanation:
If we need to be at least 98% certain that an enemy plane flying over will be detected by at least one station, we must ensure that there is at most a 2% chance that no radar stations detect the plane.
The probability that a single radar station does not detect the plane is 0.35.
For n radar stations:

Rounding up to the next whole station, at least 4 stations are needed.
Answer:
8 days
Step-by-step explanation:
20,000-10,000=10,000
10,000/1,250= 8
so it would take 8 days
Answer:
$19.8
Step-by-step explanation:
To find the answer, find the ratio.