Mark M. answered • 05/09/20

Retired math prof. Calc 1, 2 and AP Calculus tutoring experience.

Since f'(x) < 0, f is decreasing on the interval

Since f"(x) < 0, the function is also concave down.

Since f is decreasing and concave down, the left endpoint method is the only one that overestimates. So, the left endpoint rule gives 0.8895.

The right endpoint rule would give the "worst" underestimate, 0.7915.

The trapezoid rule value is the average of the left and right endpoint estimates, 0.8405

That leaves 0.8421 and 0.8410.

I'll let you decide which is which.