In 1993, the life expectancy of males in a certain country was 71.5 years. In 1998, it was 73.6 years. Let E represent the life expectancy in year t and let t represent the number.

And then what? Do they want a linear curve fit?

Assume that the life expectancy increases 0.42 years per year.

E = 71.5 + 0.42 t
if t is in years.

To represent the life expectancy in year t, we can use the variable E. We can also use the variable t to represent the number of years.

In 1993, the life expectancy of males in the certain country was 71.5 years. Thus, we can write this equation: E = 71.5 when t = 1993.

In 1998, the life expectancy increased to 73.6 years. So, we can write the equation: E = 73.6 when t = 1998.

To find the equation that represents the change in life expectancy over time, we need to determine the relationship between the years and life expectancy. We can do this by finding the slope of the line that connects the two points (1993, 71.5) and (1998, 73.6).

First, let's calculate the change in life expectancy: (73.6 - 71.5) = 2.1.

Next, let's calculate the change in years: (1998 - 1993) = 5.

Now, we can calculate the slope by dividing the change in life expectancy by the change in years: 2.1 / 5 = 0.42.

The equation representing the change in life expectancy over time can be expressed as: E = 0.42t + b, where t represents the number of years, and b is a constant term that needs to be determined.

To find the value of b, we can substitute the values of E and t from either of the given years' data. Let's use the year 1993: 71.5 = 0.42 * 1993 + b.

Simplifying the equation, we have: 71.5 = 836.46 + b.

Now, subtracting 836.46 from both sides: 71.5 - 836.46 = b.

Simplifying, we find that b ≈ -764.96.

Therefore, the equation representing the life expectancy in year t is E = 0.42t - 764.96.