Suppose You Want to Use the Midpoint Rule with N $\int _ { 1 } ^ { 6 } e ^ { - x } d x$

Multiple Choice

Suppose you want to use the Midpoint Rule with n = 4 and equal-length subintervals to approximate $\int _ { 1 } ^ { 6 } e ^ { - x } d x$ ? What is ?x used for this approximation?

A) 1
B) 5/4
C) 5/2
D) 4
E) 5