#### Answer

a. $0.02$
b. $T=56.98+x*0.02$
c. $58.98$

#### Work Step by Step

a.
To estimate the yearly increase in the average global temperature, we need to:
1. subtract the number from the first recorded year (1950) from the last recorded year (2010).
2. divide the result by the number of years between them.
$58.11-56.98=1.13$
$1.13\div60\approx0.02$
(We're rounding the result to the nearest hundredth, as instructed in the exercise).
The estimated average yearly increase is $0.02$ degrees.
b.
The mathematical model looks like this:
$T=56.98+x*0.02$
T is the temperature in degrees Fahrenheit.
56.98 is the value in 1950.
x is the number of years after 1950 for which we are calculating.
0.02 is the estimated average yearly increase.
c.
The average temperature in 2050, calculated with our mathematical model, would be:
$T=56.98+(2050-1950)*0.02=56.98+2=58.98$