Topic 13.1: Trapezoidal Rule (Questions)

Contents Previous Chapter Start of Chapter Previous Topic Introduction Notes Theory HOWTO Examples Engineering Error Questions Matlab Maple Next Topic Next Chapter

Question 1

Approximate the integral of f(x) = e-x on [0, 10] using the trapezoidal rule.

Answer: 5.00022699964881

Question 2

Approximate the integral of f(x) = x2 on the interval [0, 2] using the trapezoidal rule.

Answer: 4

Question 3

What is the estimated error (using the mean of the 2nd derivative) for the approximate in Question 2 when using eight intervals and what is the actual error?

Answer: the estimated and actual errors are equal −4/3 because the second derivative of x2 is 2.

Question 4

Approximate the integral of f(x) = x4 on the interval [0, 2] using the trapezoidal rule.

Answer: 16

Question 5

What is the estimated error for the approximation in Question 4 what is the actual error?

Answer: the estimated of the error is −32/3 = −10.6667 whereas the actual error is −48/5 = −9.6 .

Copyright ©2005 by Douglas Wilhelm Harder. All rights reserved.