If a coin is tossed 3 times and all 3 are heads, what is the probability of the fourth toss being heads?
投掷3次硬币，3次都是正面向上，投掷第四次正面向上的可能性是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>