Recognize and use the scientific method...know these terms observable testable and repeatable

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.