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Answer:
arc FG = 115°
arc EG = 165°
Step-by-step explanation:
The first step is to understand how these arcs are arranged on a circle. The next step is to realize the whole is the sum of the parts. Arcs have the same measure as their central angle. A circle totals 360°.
arc EF + arc FG = arc EFG . . . . parts of an arc add to give the whole arc
80° + arc FG = 195°
arc FG = 115° . . . . . . . . . subtract 80°
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Similarly, parts of a circle add to give the whole circle.
arc EFG + arc EG = 360°
195° + arc EG = 360°
arc EG = 165° . . . . . . . . . subtract 195°
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The probability of at least three heads can be found by<span><span>∑<span>k=3</span>4</span><span>(<span>4k</span>)</span><span>.5k</span><span>.5<span>4−k</span></span>=<span>516</span></span></span>