For 1983 through 1989, the per capita consumption of chicken in the U.S. increased at a
rate that was approximately linear. In 1983,
the per capita consumption was 37.1 pounds,
and in 1989 it was 50 pounds.
Write a linear model for per capita consumption
of chicken in the U.S. Let t represent
time in years, where t = 3 represents
1983. Let y represent chicken consumption in
pounds.

y = 43.55 + 2.15t

Explanation:

We were told that in 1983, the per capita consumption was 37.1 pounds, and in 1989 it was 50 pounds.

If we assume t = 0 corresponds to year 1980. Then, for 1983 it will be t = 3 and for 1989,it will be t = 9.

Thus, expressing the information as ordered pairs, we have; (3,37. 1) and (9,50).

Let us now find slope of the linear function:

m1 = (y2 - y1)/(t2 - t1)

m1 = (50 - 37.1)/(9 - 3)

m1 = 2.15

So, we can find the linear equation as;

y - 37.1 = 2.15(t - 3)

y = 37.1 + 2.15t - 6.45

y = 43.55 + 2.15t

Your answer is electricity, light and magnetism.  They can be determined usinf elecromagnetic radioation. 

Even the energy  can't be detected by our eyes, there are a lot of measurement  instruments that can measure infrared (IR), gamma rays, radio or X-rays or ultraviolet (UV)