# Chapter 12 - Counting and Probability - Section 12.3 Probability - 12.3 Assess Your Understanding - Page 885: 28

$P(T)=\dfrac{1}{3}$, and $P(H)=\dfrac{2}{3}.$

#### Work Step by Step

If $T$:tails, $H$: heads, then if $P(T)=x$, then $P(H)=2x.$ We know that $P(T)+P(H)=1\\x+2x=1\\3x=0\\x=\dfrac{1}{3}$. Thus $P(T)=\dfrac{1}{3}$, and $P(H)=\dfrac{2}{3}.$

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