## Elementary Technical Mathematics

$53.\overline{3}\%$
First, find the increase in pressure: $=115-75 \\=40\text{ lb/in}^2$ RECALL: $\text{percent increase}=\dfrac{\text{increase in value}}{\text{original value}}$ The given problem has: original value =$75 \text{ lb/in}^2$ increase in value = $40 \text{ lb/in}^2$ Solve for the percent increase using the formula above to obtain: percent increase $= \dfrac{40}{75} \\=0.5\overline{3} \\=0.5\overline{3} \times 100\% \\=43.\overline{3}\%$ Thus, there was an $53.\overline{3}\%$ increase in pressure.