Answer
1.56$\frac{hours/day}{adult}$
Work Step by Step
You have to find how many total average hours spent online in a year per each adult: $\frac{93000000000 hours}{163000000adults}$ $\approx$ 570.55 $\frac{hours}{adult}$.
To find the average hours per day per adult in a year, divide by 365 days because there are 365 days in a year: $\frac{570.55{\frac{hours}{adult}}}{365 days}$
=1.56$\frac{hours/day}{adult}$