7176 rounded to 1 significant figure

Acoin is tossed twice. let e e be the event "the first toss shows heads" and f f the event "the second toss shows heads". (a) are the events e e and f f independent? input yes or no here: yes (b) find the probability of showing heads on both toss. input your answer here: preview

What could explain what happened when the time was equal to 120 minutes

Precalculus question, image attached.