Why is it necessary to be able to replicate the results of a scientific experiment

Idon’t quite understand this problem

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

An object moves from position +34m to the position -15m in 15 seconds. what is the total displacement? what is the total velocity?