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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>
3s+28=85, take away 28 from both sides of the equals to give you 3s=57, divide by 3 on both side to give you s=19.
Answer: 14
Step-by-step explanation:
