During the cold winter months, a sheet of ice covers a lake near the arctic circle. at the beginning of spring, the ice starts to melt. the variable s models the ice sheets thickness in meters t weeks after the beginning of spring s=-0.25t+4 by how much does the ice sheets thickness decrease every 6 weeks

1.5 meters.

Step-by-step explanation:

Given: At the beginning of spring, the ice starts to melt.

The variable s models the ice sheets thickness in meters t weeks after the beginning of spring.

At t=0, s=4 meters

At t=1, s=3.75 meters

∴It is a linear equation, where the rate of change in thickness = 3.75-4=0.25 meter per minute .

The decrease in ice sheet in every  6 weeks =

To obtain the quadratic equation for the data set given, i have used excel spread sheet, this is shown in the attachment below. the equation is: y=-0.4931x²+23.38x+996.03b]the density of the sample at depth of 20 m will be : f(20)=-0.4931(20)²+23.38(20)+996.03f(20)=1266.39