Practice Approximation in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A value intentionally chosen to be close to but not exactly equal to the true value, with a known or estimated error.

We use 3.14 for ฯ€\pi, knowing it's not exactly right but close enough.

Showing a random 20 of 50 problems.

Example 1

medium
Compute the percent error when ฯ€\pi is approximated as 3.143.14 (use the true value 3.141593.14159).

Example 2

medium
Use the first-order linear approximation a+ฯตโ‰ˆa+ฯต2a\sqrt{a+\epsilon} \approx \sqrt{a} + \dfrac{\epsilon}{2\sqrt{a}} to estimate 101\sqrt{101}.

Example 3

easy
Round 0.04670.0467 to two decimal places.

Example 4

hard
A circular table has measured diameter 1.201.20 m (with ยฑ0.005\pm 0.005 m uncertainty). Approximate its area and its uncertainty.

Example 5

easy
Estimate 198ร—52198 \times 52 using rounding, then compute the exact answer and find the percent error.

Example 6

easy
Estimate 50\sqrt{50} to one decimal place without a calculator.

Example 7

challenge
Estimate 2โ‰ˆ1.4\sqrt{2} \approx 1.4 and use one Newton step x1=12(x0+2x0)x_1 = \frac{1}{2}(x_0 + \frac{2}{x_0}) to improve it.

Example 8

medium
Use the approximation ฯ€โ‰ˆ227\pi \approx \dfrac{22}{7} to estimate the circumference and area of a circle with radius 1414 cm. Compare with the decimal approximation ฯ€โ‰ˆ3.14159\pi \approx 3.14159.

Example 9

medium
To estimate 20\sqrt{20} between consecutive tenths, which two values bracket it?

Example 10

easy
True or false: every approximation has some error.

Example 11

easy
Round ฯ€\pi to two decimal places.

Example 12

medium
A budget of $2980\$2980 is rounded to $3000\$3000 for a report. What is the rounding error, and is it an over- or under-estimate?

Example 13

challenge
A surveyor estimates a hill's height using the angle of elevation. If the measured angle is 30.0โˆ˜ยฑ0.5โˆ˜30.0^\circ \pm 0.5^\circ and the horizontal distance is 200200 m (exact), give the approximate height and its uncertainty.

Example 14

easy
Estimate ฯ€\pi to 11 decimal place.

Example 15

medium
Approximate 1,492รท71{,}492 \div 7 to the nearest hundred.

Example 16

hard
Use the linear approximation (1+x)nโ‰ˆ1+nx(1 + x)^n \approx 1 + nx for small xx to estimate 1.02101.02^{10}.

Example 17

easy
Approximate 17\sqrt{17} to the nearest whole number.

Example 18

easy
Approximate 227\frac{22}{7} as a decimal to two places.

Example 19

hard
What is the relative error if a measurement of 50.050.0 kg is off by 0.40.4 kg?

Example 20

easy
Round 68496849 to the nearest hundred.