Riemann Sums: Videos & Practice Problems

The time (in minutes) it takes to assemble a certain product is normally distributed with a mean of $45$ minutes and a standard deviation of $8$ minutes. The fraction of assembly times between $a$ and $b$ (with ) minutes is represented by the integral $\frac{1}{8\sqrt{2\pi }}{\int }_a^b{e}^{-\frac{1}{2}(\frac{x-45}{8}{)}^2}dx$. What percentage of assemblies are completed between $40$ and $56$ minutes? Use the Trapezoid Rule with $8$ subintervals to estimate your answer.