A passenger fell asleep when the train was halfway through the journey. Waking up to find that the journey to his destination was half the distance traveled by the train while he was asleep. The total travel time is 4 hours, how many hours will it take for him to arrive after he wakes up?
某旅客在火车走完一半旅程时睡着了．醒来发现到达目的地的路程占他睡着时火车所行路程的一半．全程行驶时间是4小时，他醒来后还要几小时才能到达？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 * (1/2) * (1/2) * 4</gadget>
<output>1</output>

<result>1</result>