the change in the deflection with every 100 pounds is,
[tex]=\frac{0.5-0}{100-0}[/tex][tex]=\frac{0.5}{100}[/tex]so for every 50 pounds will be,
[tex]\begin{gathered} =(\frac{\frac{0.5}{100}}{2}) \\ =\frac{0.5}{200} \\ =0.0025 \end{gathered}[/tex]so for every 50 pound increase in the weight, the change in the deflection is 0.25