Exercise 77 Page 238

Practice makes perfect

a A coin has two sides, which means the probability of flipping either side is 12.

P(heads)=1/2 [0.8em] P(tails)=1/2

If we multiply the probability of flipping each side by their respective value and add the products, we get the expected value from one coin flip.

Event	P	Value	P* Value	Expected Value
Heads	1/2	4	1/2* 4	2
Tails	1/2	-7	1/2* ( -7)	-3.5

The expected earnings from one flip of the coin is the sum of the expected value for each side.

2+(- 3.5)

AddNeg

a+(- b)=a-b

2-3.5

SubTerm

Subtract term

- 1.5

The expected value from one coin toss is - $1.50.

b From Part A we know that the expected value from one coin toss is - $1.50. Therefore, after 8 coin tosses the expected value should be this number multiplied by 8.

(- $1.50)(8)=- $ 12

Subchapter links

4.2.1 Sine and Cosine Ratios p.232-234

4.2.2 Selecting a Trig Tool p.237-238

4.2.3 Inverse Trigonometry p.241-242

4.2.4 Trigonometric Applications p.245-247

Exercise 77 Page 238

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