Answer:
1 hr on problems and 3 reading
Explanation:
1 hr on problems bc he's able to finish 40 problems which is better than reading for 1 hr since the teacher said reading for 1 hr is equivalent to solving 35 problems. in the 2nd, 3rd and 4th hours he solves less than 35 problems each hour so it's better to just read for an hour.
Experimenter bias can best be controlled using Double-blind control.
Answer:
They divide the Earth into 4 geographical sides. The lines can help travelers and people for this reason.
