Trapezoidal Rule

Trapezoidal sums and the trapezoidal rule, including from tabular data.

← All learning targets

Trapezoidal Rule

31 questions

Average Value Using Trapezoidal Rule

The table provides a person's cholesterol level at selected times during a 10-week treatment period.

Time (weeks)02610
Level210200190180

What is the average cholesterol level over the 10-week period, approximated by a trapezoidal sum with the subintervals [0, 2], [2, 6], and [6, 10]?

  1. A.

    193

  2. B.

    195

  3. C.

    188

  4. D.

    198

Correct answer: A
Comparing Midpoint and Trapezoidal Sums

Which of the following statements best describes the primary difference in the calculation of a midpoint Riemann sum and a trapezoidal sum?

  1. A.

    Midpoint uses left endpoints; trapezoidal uses right

  2. B.

    Midpoint uses midpoints; trapezoidal uses endpoints

  3. C.

    Midpoint uses right endpoints; trapezoidal uses left

  4. D.

    Midpoint uses endpoints; trapezoidal uses midpoints

Correct answer: B
Comparing Trapezoidal and Riemann Sums

What is a primary advantage of approximating a definite integral with a trapezoidal sum instead of a left or right Riemann sum?

  1. A.

    Uses only midpoints for accuracy

  2. B.

    Easier computation with nonuniform partitions

  3. C.

    Requires fewer calculations overall

  4. D.

    Better approximation with fewer subintervals

Correct answer: D
Properties Of The Trapezoidal Rule

All of the following statements concerning trapezoidal sums are true EXCEPT:

x025
f(x)3711
  1. A.

    The trapezoidal rule computes the area by averaging the function values at the endpoints of each subinterval and multiplying by the subinterval's width.

  2. B.

    Smaller subinterval widths generally improve the accuracy of the trapezoidal sum approximation.

  3. C.

    The trapezoidal rule approximation always gives an underestimate of the definite integral for any continuous function.

  4. D.

    For functions with varying concavity, the trapezoidal rule may either overestimate or underestimate the true area.

Correct answer: C
Solving for a Value Using Trapezoidal Rule
$$x$$0246
$$f(x)$$4$$k$$812

The table above shows selected values for a function $$f$$ that is continuous on the closed interval $$[0, 6]$$. If the trapezoidal approximation of $$\displaystyle \int_{0}^{6} f(x) dx$$ using three subintervals of equal length is 52, what is the value of $$k$$?

  1. A.

    6

  2. B.

    2

  3. C.

    10

  4. D.

    14

Correct answer: C
Trapezoidal Area Approximation

Which of the following methods approximates the area under a curve using a collection of trapezoids?

  1. A.

    Trapezoidal Sum

  2. B.

    Midpoint Sum that uses midpoints of subintervals for rectangles

  3. C.

    Right-Handed Riemann Sum approximated by using right endpoints to form rectangles

  4. D.

    Left-Handed Riemann Sum approximated by using left endpoints to form rectangles

Correct answer: A
Trapezoidal Rule Application

The trapezoidal rule applied to a function f on the subintervals [0, 2] and [2, 4] yields an area of 28, as represented by the equation below. What is the value of f(2)?

$$\frac{1}{2}(3+f(2))(2-0) + \frac{1}{2}(f(2)+11)(4-2)=28$$

  1. A.

    $$7+\frac{1}{2}$$

  2. B.

    $$5$$

  3. C.

    $$8$$

  4. D.

    $$7$$

Correct answer: D
Trapezoidal Rule Application

The equation $$\frac{1}{2}(H(2)+H(3))(3-2) = 3.25$$ represents the approximation of an integral using a single trapezoid. If $$H(2) = 1.5$$, what is the value of $$H(3)$$?

  1. A.

    $$6$$

  2. B.

    $$3.25$$

  3. C.

    $$5$$

  4. D.

    $$4.5$$

Correct answer: C
Trapezoidal Rule Approximation

Using the graph of $$f(x)=\ln(x)$$ on the interval $$[1,4]$$, approximate the definite integral $$\int_{1}^{4} \ln(x) dx$$ by applying the trapezoidal rule with 3 equal subintervals.

  1. A.

    Approximately $$2.60$$ after a rounding error.

  2. B.

    $$2.48$$

  3. C.

    $$2.35$$

  4. D.

    $$2.50$$

Correct answer: B
Trapezoidal Rule Approximation

Using the trapezoidal rule with $$n=2$$, which of the following is an approximation for $$\int_{1}^{3} \ln(x) dx$$?

  1. A.

    1.2425

  2. B.

    0.8109

  3. C.

    1.0986

  4. D.

    1.3863

Correct answer: A
Trapezoidal Rule Approximation Error

The magnitude of the error in a trapezoidal rule approximation is determined for `n = 10, 20, 40,` and `80` subintervals. Which of the following lists these values of `n` in order from the one that yields the largest error to the one that yields the smallest error?

  1. A.

    n = 80, n = 40, n = 20, n = 10

  2. B.

    n = 20, n = 10, n = 40, n = 80

  3. C.

    n = 10, n = 20, n = 40, n = 80

  4. D.

    n = 10, n = 40, n = 20, n = 80

Correct answer: C
Trapezoidal Rule Approximation From a Table

The table shows values for a function $$f$$ at selected times $$t$$. Which of the following expressions gives the trapezoidal approximation of $$\int_{0}^{6} f(t) dt$$ using the three subintervals indicated by the table?

t (s)0136
f(t)24814
  1. A.

    $$1*4 + 2*8 + 3*14$$

  2. B.

    $$1*2 + 2*4 + 3*8$$

  3. C.

    $$\frac{(2+4+8+14)}{4} * 6$$

  4. D.

    $$\frac{1}{2}*(2+4)*1 + \frac{1}{2}*(4+8)*2 + \frac{1}{2}*(8+14)*3$$

Correct answer: D
Trapezoidal Rule Approximation From a Table

The table below gives selected values for a continuous function $$f$$.

x012345
f(x)31-2047

Using the trapezoidal rule with the five subintervals indicated by the table, what is the approximate value of $$\int_{0}^{5} f(x) dx$$?

  1. A.

    7.5

  2. B.

    10

  3. C.

    13.5

  4. D.

    13

Correct answer: A
Trapezoidal Rule Area Approximation

Using the graph of $$f(x)=\cos(x)$$ on the interval $$[0,\frac{\pi}{2}]$$, approximate the area under the curve using the trapezoidal rule with 2 subintervals.

  1. A.

    $$0.79$$

  2. B.

    $$0.95$$

  3. C.

    $$1.05$$

  4. D.

    Approximately $$1.00$$ due to mis-calculation of endpoints.

Correct answer: B
Trapezoidal Rule Area Approximation

Based on the graph above representing $$f(x)=x^2$$, which of the following is true regarding the trapezoidal approximation of the area under the curve on the interval from $$x=1$$ to $$x=3$$ using a single trapezoid?

  1. A.

    The area approximated by the trapezoid is $$8$$, which underestimates the area.

  2. B.

    The area approximated by the trapezoid is $$12$$ because the average of the endpoints is overestimated.

  3. C.

    The area approximated by the trapezoid is $$10$$.

  4. D.

    The area approximated by the trapezoid is $$9$$ by mistakenly using the midpoint value.

Correct answer: C
Trapezoidal Rule Area Approximation from a Table

The table above shows selected values for a function H. Use a trapezoidal sum with the subintervals indicated by the data to approximate the area under the curve of H from t = 2 to t = 10.

Years (t)235710
H(t)1.5261115
  1. A.

    $$67.00$$

  2. B.

    $$66.25$$

  3. C.

    $$64.50$$

  4. D.

    $$65.75$$

Correct answer: D
Trapezoidal Rule Error Approximation

The error in the trapezoidal rule approximation of $\displaystyle\int_{0}^{1}$ eˣ dx with n = 4 subintervals is most nearly:

  1. A.

    -0.0104

  2. B.

    -0.0208

  3. C.

    0.0104

  4. D.

    0.0208

Correct answer: A
Trapezoidal Rule Procedure

The table shows values for a function `H(t)`. Which of the following correctly orders the steps for approximating the area under the curve of `H` using a trapezoidal sum with the subintervals indicated by the table?

Years (t)235710
Height H(t)1.5261115
  1. A.

    Determine subinterval widths from the table, Compute the average of each pair of consecutive function values, Multiply each average by the corresponding subinterval width, Sum these products to approximate the area

  2. B.

    Determine subinterval widths from the table, Multiply each average by the corresponding subinterval width, Compute the average of each pair of consecutive function values, Sum these products to approximate the area

  3. C.

    Compute the average of each pair of consecutive function values, Determine subinterval widths from the table, Multiply each average by the corresponding subinterval width, Sum these products to approximate the area

  4. D.

    Sum these products to approximate the area, Determine subinterval widths from the table, Compute the average of each pair of consecutive function values, Multiply each average by the corresponding subinterval width

Correct answer: A
Trapezoidal Sum Approximation

The area under the curve $$y=3x^2$$ on the interval $$[0, 2]$$ is approximated using a trapezoidal sum with two subintervals of equal width. What is the value of this approximation?

  1. A.

    8.25

  2. B.

    10

  3. C.

    9

  4. D.

    7.5

Correct answer: C
Trapezoidal Sum Approximation

What is the trapezoidal sum approximation for $$\int_{1}^{6} (2x - 1) dx$$ using five equal subintervals?

  1. A.

    25

  2. B.

    20

  3. C.

    30

  4. D.

    35

Correct answer: C
Trapezoidal Sum Approximation From a Table

Use a trapezoidal sum with two subintervals indicated by the table to approximate the value of $$\int_{0}^{4} f(x) dx$$.

xf(x)
03
25
49
  1. A.

    $$22$$

  2. B.

    $$24$$

  3. C.

    $$20$$

  4. D.

    $$26$$

Correct answer: A
Trapezoidal Sum Approximation From A Table

The table shows values of a function `f` for selected values of `x`. Which of the following expressions represents the trapezoidal sum approximation of $$\int_{0}^{7} f(x) dx$$?

x0247
f(x)161015
  1. A.

    $$2*6 + 2*10 + 3*15$$

  2. B.

    $$\frac{1}{2}*(1+6)*2 + \frac{1}{2}*(6+10)*2 + \frac{1}{2}*(10+15)*3$$

  3. C.

    $$\frac{1}{2}*(1+6+10+15)*7$$

  4. D.

    $$2*1 + 2*6 + 3*10$$

Correct answer: B
Trapezoidal Sum Approximation From a Table

The table below provides selected values for a function $H(t)$. Using a trapezoidal sum with the four subintervals indicated by the table, what is the approximation of $$\int_{2}^{10} H(t) dt$$?

Years (t)Height H(t)
21.5
32
56
711
1015
  1. A.

    68.3

  2. B.

    70.2

  3. C.

    60.5

  4. D.

    65.75

Correct answer: D
Trapezoidal Sum Approximation From a Table

The table provides selected values for a function `H`. Use a trapezoidal sum with the subintervals indicated in the table to approximate $$\int_{2}^{10} H(t) dt$$.

Years (t)235710
Height H(t)1.5261115
  1. A.

    $$67.75$$

  2. B.

    $$65.25$$

  3. C.

    $$66.75$$

  4. D.

    $$65.75$$

Correct answer: D
Trapezoidal Sum Area Formula

In a trapezoidal Riemann sum, how is the area of a single trapezoid calculated?

  1. A.

    By multiplying the base by the average of the two heights.

  2. B.

    By adding the base to the product of the two heights.

  3. C.

    By multiplying the base by the difference of the two heights.

  4. D.

    By dividing the base by the sum of the two heights.

Correct answer: A
Trapezoidal Sum From a Table

The table below gives selected values for a function $H$. Which of the following shows the correct calculation for a trapezoidal sum approximation of $$\int_{2}^{10} H(t) dt$$?

$t$235710
$H(t)$1.5261115
  1. A.

    Trapezoidal Sum = $$ (1.5+2+6+11+15)/5 = 7.7 $$

  2. B.

    Trapezoidal Sum = $$\frac{1}{2}[(1.5+2)+(2+6)+(6+11)+(11+15)]*(1+2+2+3)= 109$$

  3. C.

    Trapezoidal Sum = $$ (1.5+2)*1+(2+6)*2+(6+11)*2+(11+15)*3 = 131.5$$ (missing the 1/2 factor)

  4. D.

    Trapezoidal Sum = $$\frac{1}{2}(1.5+2)*1+\frac{1}{2}(2+6)*2+\frac{1}{2}(6+11)*2+\frac{1}{2}(11+15)*3 = 65.75$$

Correct answer: D
Trapezoidal Sum From Table Data

The table shows values for a function H at selected values of t. Which of the following is true about the trapezoidal approximation of $$ \int_{2}^{10} H(t) dt $$ using the subintervals given by the data in the table?

| Years (t) | 2 | 3 | 5 | 7 | 10 |
| Height (H(t)) | 1.5 | 2 | 6 | 11 | 15 |

  1. A.

    The trapezoidal sum equals $$70$$ due to an overestimation of the average heights.

  2. B.

    The trapezoidal sum equals $$60$$ by erroneously assuming uniform subinterval widths.

  3. C.

    The trapezoidal sum equals $$65.75$$.

  4. D.

    The trapezoidal sum equals $$55.5$$ from an arithmetic miscalculation.

Correct answer: C
Trapezoidal Sum From Table Data

The table provides selected values for a function $$H$$. Using a trapezoidal sum with the subintervals indicated by the table, which of the following expressions approximates $$\int_{2}^{10} H(t) dt$$?

t235710
H(t)1.5261115
  1. A.

    $$\frac{1}{2}*((1.5+2)*1+(2+6)*2+(6+11)*2)$$

  2. B.

    $$\frac{1}{2}*((1.5+2)*1+(2+6)*2+(6+11)*2+(11+15)*3)$$

  3. C.

    $$2*[(1.5+2+6+11+15)]$$

  4. D.

    $$1.5*1+2*2+6*2+11*3$$

Correct answer: B
Trapezoidal Sum from Tabular Data

The table below provides values for a function H at selected times t.

Years:(t)235710
Height:H(t)1.5261115

Which of the following expressions gives the trapezoidal approximation of the integral of H(t) from t=2 to t=10, using the subintervals indicated by the data in the table?

I.

$$\frac{1}{2}*(1.5+2)*1 + \frac{1}{2}*(2+6)*2 + \frac{1}{2}*(6+11)*2 + \frac{1}{2}*(11+15)*3$$

II.

$$1*(1.5) + 2*(2) + 2*(6) + 3*(11)$$

III.

$$\frac{1}{2}*(2+6)*1 + \frac{1}{2}*(6+11)*2 + \frac{1}{2}*(11+15)*3$$

  1. A.

    II only

  2. B.

    I and II

  3. C.

    III only

  4. D.

    I only

Correct answer: D
Trapezoidal Sum From Tabular Data

A table extracted from the graph provides the following values for a function $$H(t)$$:

Years (t)235710
H(t)1.5261115

Using the trapezoidal rule, estimate the definite integral of $$H(t)$$ with respect to t over the interval from 2 to 10.

  1. A.

    Around $$72.50$$ resulting from miscalculating the interval widths.

  2. B.

    $$65.75$$

  3. C.

    Approximately $$68$$

  4. D.

    $$61.75$$

Correct answer: B
Trapezoidal Sum With Unequal Subintervals

The table provides selected values for a function `f`. Which of the following shows the correct computation for a trapezoidal sum approximation of $$\int_{0}^{6} f(x) dx$$ using the three subintervals indicated by the data?

x0136
f(x)23814
  1. A.

    Trapezoidal Sum = $$\frac{21+29}{2}=25$$

  2. B.

    Trapezoidal Sum = $$\frac{1}{2}(2+3)*1+\frac{1}{2}(3+8)*2+\frac{1}{2}(8+14)*3=46.5$$

  3. C.

    Trapezoidal Sum = $$\frac{1}{2}(2+3)+\frac{1}{2}(3+8)+\frac{1}{2}(8+14)=27.5$$

  4. D.

    Trapezoidal Sum = $$ (2+3+8+14)*1 = 27$$

Correct answer: B