Question 156551
{{{y = (x(2001) - x(1991)) / (2001 - 1991)}}}
that's the formula to use to determine the average increase in salary per year.
substituting values, the formula becomes
{{{y = (1410000 - 266000) / (2001 - 1991)}}}
resulting in
{{{y = 1144000 / 10}}}
resulting in
{{{y = 114400}}} dollars increase in each year.
formula for estimating future salaries would then become.
{{{y = 1410000 + (n * 114400)}}}
where n is the number of years from 2001.
testing the formula using original data, the formula would become
{{{y = 266000 + (10 * 114400)}}}
which becomes
{{{y = 266000 + 1144000}}}
which becomes
{{{y = 1410000}}}
where 266000 was the salary in 1991 and 1410000 is the salary 10 years later (2001).