Suppose that we want to estimate what percentage of all drivers exceed the 50 km/h speed limit on a certain stretch of road. (a) (10 points) How large a sample will we need to be at least 99%...

Suppose that we want to estimate what percentage of all drivers exceed the
50 km/h speed limit on a certain stretch of road.
(a) (10 points) How large a sample will we need to be at least 99% confident that the error
of our estimate, the sample percentage, is at most 3.5% ?
(b) (10 points) How large a sample will we need if we know that 20% of the drivers in a
preliminary sample exceed the 50 km/h speed limit on that stretch of road.