4.5: Geometric Probability p M(DSP)–10–5 Solves problems involving experimental or theoretical probability. GSE’s Primary Secondary GSE’s M(G&M)–10–2 Makes and defends conjectures, constructs geometric arguments, uses geometric properties, or uses theorems to solve problems involving angles, lines, polygons, circles, or right triangle ratios (sine, cosine, tangent) within mathematics or across disciplines or contexts (e.g., Pythagorean Theorem, Triangle Inequality Theorem). M(G&M)–10–6 Solves problems involving perimeter, circumference, or area of two dimensional figures (including composite figures) or surface area or volume of three Primary GSE

Probability=

Probability Definition - a # from ______________ that represents the chance that an event will occur.Definition - a # from ______________ that represents the chance that an event will occur. 0 –0 – 1 – ________chance (the event will always occur).1 – ________chance (the event will always occur)..5 or ½ - 50% chance.5 or ½ - 50% chance 01 No chanceDef. gonna happen.5 Could go either way

Geometric Probability – probabilityGeometric Probability – probability involving _________ or ______________. ______________.

Length Probability Postulate If a point on AB is chosen at random and C is between A and B, then the probability that the point is on AC is Length of AC Length of AB

Example Find the probability that a point chosen at random in AF is also part of each of the segments

Area Problems If a point in a region A is chosen at random, then the probability that the point is in region B, which is in the interior region A, is *Note. Does not always have to be same shapes. Could be a circle inside a square, triangle inside a circle, etc. Remember the formulas.

Example A common game is darts. What is the probability of randomly throwing a dart such that it hits within the red area, given that the dart will always land within the boundary of the outer circle? P(Red)= 1 5

Problems A dart is thrown at random onto a board that has the shape of a circle as shown below. Calculate the probability that the dart will hit the shaded region. (Use π =3.14 )

If a dog had an accident in the house, what is the probability of it occurring in the bedroom ?

Problem The figure shows a circle divided into sectors of different colors. If a point is selected at random in the circle, calculate the probability that it lies: a) in the red sector. b) in the green sector. c) in the blue sector. d) in any sector except the green sector.

Square ABCO contains part of a circle. What is the probability that a point Chosen at random would be in the shaded part?

Problem An arrow is shot at random onto the rectangle PQRS. Calculate the probability that the arrow strikes: a) triangle AQB. b) a shaded region. c) either triangle BRC or the unshaded region. In the figure below, PQRS is a rectangle, and A, B, C, D are the midpoints of the respective sides as shown.

Homework