3y = 150000 + 1100x ; x as time in years and y as amount of investment after x years.
[tex]\textrm{rate at which market is growing}= \frac{\textrm{Growth in the investment}}{\textrm{Number of years passed to grow}}[/tex]
Growth in John's investment between year 2005 and 2011 = $(52200 - 50000) = $2200
Years passed to grow that much = 2011 - 2005 = 6 years
[tex]\textrm{rate}=\frac{2200}{6}[/tex]
[tex]\mathbf{rate=\frac{1100}{3}}[/tex]
Value of investment after x years = (Initial investment) + (Rate of growth) × (Years of investment)
Value of investment = y
Years of investment = x
rate of growth = [tex]\frac{1100}{3}[/tex]
Initial investment = $50000
[tex]\mathbf{y=50000+\frac{1100}{3}\times x}[/tex]
∴ 3y = 150000 + 1100x
slope of above equation of line is [tex]\mathbf{\frac{1100}{3}}[/tex] which the rate of growth of market.
