Geometric Probability Worksheet

Fifteen numbered geometry problems, ten of them shaded-area and shaded-length probability targets and five reviewing radicals, composite areas and right-triangle trigonometry, each reprinted with a full worked solution.
Grades
Grades 10–12
Pages
6
File type
PDF
Answer key
Included

Updated Sep 18, 2021

Subject
Geometry, Math
Topic
Geometry, Probability
Resource types
Worksheets
Answer key
Included

From the author

About this resource

This review guide comes with an answer key!

In the classroom

Teaching tips & learning objectives

Learning objectives

  • Calculate the probability that a randomly thrown dart lands in a shaded region by forming the ratio of shaded area to total area

  • Transfer the same ratio idea to one dimension, comparing a shaded length such as a 13-unit hypotenuse or a 6π in arc against a total perimeter

  • Use the relationship shaded area + unshaded area = total area to reach an answer through whichever region is easier to compute

  • Write square roots in simplified radical form and recognise which of √40 to √49 are already simplified

  • Solve a right triangle for unknown sides, area and perimeter using cosine and sine of a given 28° angle, rounded to the nearest hundredth with units

Teaching tips

  • The sheet opens with a blank "Appoint a reader" line, so decide before handing it out whether groups will name that reader or the line will simply be left unused

  • Problem 6 carries its own hint, telling students the radius of one of four circles across a 24 cm square is "NOT 12 cm"; it works well as the figure you model on the board first

  • Item 11 asks for the words "ALREADY SIMPLIFIED" on any radical that cannot be reduced, so remind students that leaving the entry blank is not the same response

  • Answers on the worked pages are given in exact form and then as a decimal, which lets you accept either 16 - 3π over 16 or 0.411 depending on what the class is practising

  • Problems 12 through 15 sit on the last page and can be assigned separately as a special-right-triangle and radicals review without touching the probability items

Skills covered

  • Geometric probability from area — students compute the shaded-to-total ratio for figures such as a 6 in circle inscribed in a square (36π/144) and four circles packed inside a 24 cm square (576 - 108π over 576).

  • Geometric probability from length — problems 7 to 9 switch the ratio to one dimension: a 13-unit hypotenuse against a 30-unit perimeter, a 6π in arc against a (12 + 6π) in semicircle perimeter, and 6 m of a 13 m segment.

  • Working with the complement — problem 6 directs students to decide whether the shaded or unshaded region is easier to calculate, then recover the other from the total 576 cm² square.

  • Simplifying radicals — item 11 has students reduce √40 to 2√10, √44 to 2√11 and √48 to 4√3, and mark the primes such as √41 and √47 as already simplified.

  • Right-triangle measurement — problems 14 and 15 apply the 30-60-90 and 45-45-90 side ratios and then cos 28° and sin 28° to find a = 6.18 ft, b = 3.29 ft, an area of 10.16 ft² and a perimeter of 16.47 ft.

Good to know

Questions teachers ask about this resource

Are the solutions written in exact form or as decimals?

The worked pages include exact forms and decimal values. Problem 15 specifies answers to the nearest hundredth with units.

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Resource details

Concepts & topics

Core concepts

  • Geometric probability

  • Area of circles and polygons

  • Perimeter and arc length

  • Simplifying radicals

  • Right triangle trigonometry

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