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10-81.

A spinner is divided into two regions. One region, red, has a central angle of $60º$. The other region is blue. 10-81 HW eTool (CPM). Homework Help ✎

1. On your paper, sketch a picture of this spinner.

2. If the spinner is spun twice, what is the probability that both spins land on blue?

Find the measures of the central angles. What fraction of the circle is red?
Use this to find the probability.

$\frac{300º}{360º} = \frac{5}{6}$

$\frac{5}{6} \cdot \frac{5}{6} = \frac{25}{36} = 69.4\% = 0.694$

3. If the radius of the spinner is $7$ cm, what is the area of the blue region?

Find the area of the whole circle, then subtract the area of the red region.

4. A different spinner has three regions: purple, mauve, and green. If the probability of landing on purple is $\frac { 1 } { 4 }$ and the probability of landing on mauve is $\frac { 2 } { 3 }$, what is the central angle of the green region?

• Find the probability of landing on the green region. Then use this to find the measure of the central angle.

$30º$

Use the eTool below to view the spinner in part (a) and create a spinner for part (d).
Click the link at right for the full version of the eTool: CCG 10-81 HW eTool.