Core Connections Geometry, 2013
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Core Connections Geometry, 2013 View details
Chapter Closure

Exercise 104 Page 390

a We are given two spinners, and the results will determine if someone is thrown in the pool. Let's first list all of the possible combinations and mark the ones that results in a sum less than 10 in red. These combinations will get you thrown in the pool.
1+5&= 6 1+7&= 8 1+9&=10 [1em] 3+5&= 8 3+7&=10 3+9&=12

Three combinations result in you getting thrown in the pool. To calculate the risk of getting these combinations, we have to consider the probability of spinning each field.

Spinner A

From the diagrams we see that one sector occupies a right angle. This means the last sector must occupy a 270^(∘) angle. With this information we can figure out the ratio that each sector occupies of the spinner.

Spinner B

In Spinner B, each sector occupies a third of the circle. Therefore, the probability of getting any sector on the second spinner is 13.

Probability Calculation

The probability of two independent events occurring is the product of the event's probabilities. P(1,5): 3/4* 1/3= 3/12 [0.8em] P(1,7): 3/4* 1/3= 3/12 [0.8em] P(3,5): 1/4* 1/3= 1/12 Finally, we will add these probabilities to get the union of all combinations that results in you getting thrown in the pool. P(thrown in the pool) [-0.8em] 3/12+ 3/12+ 1/12=7/12

b Like in Part A, we will first list all the possible combinations that will get you thrown in the pool.
2+4&= 6 && 3+4= 7 2+5&= 7 && 3+5= 8 2+6&= 8 && 3+6= 9 [1em] 4+4&= 8 && 5+4= 9 4+5&= 9 && 5+5=10 4+6&=10 && 5+6=11 A total of nine combinations gets you thrown in the pool. To calculate the risk of getting these combinations, we have to consider the probability of spinning each sector.

Spinner C

In Spinner C, each sector occupies a quarter of the circle. Therefore, the probability of getting any of the sectors on the second spinner is 14.

Spinner D

In Spinner D, each field occupies a third of the circle. Therefore, the probability of getting any of the fields on the second spinner is 13.

Probability Calculation

Again, the probability of two independent events happening is the product of these individual probabilities. In this case, though, we might want to calculate the probability of not getting thrown in the pool, as it involves less calculations. We can find the complement to this. P(4,6): 1/4* 1/3= 1/12 [0.8em] P(5,5): 1/4* 1/3= 1/12 [0.8em] P(5,6): 1/4* 1/3= 1/12 Finally, we will add these probabilities to get the union of all combinations that leads to not getting thrown in the pool and subtract the result from 1. P(thrown in the pool) [-0.8em] 1- ( 1/12+ 1/12+ 1/12)=9/12