Question

During one year about 163 million adults over 18 years old in the United States spent a total of about 93 billion hours online at home. On average, how many hours per day did each adult spent online at home?

1. How do you write each number in scientific notation?
2 How do you convert the units to hours per day.

Answer 1

one billion is 9 zeros, on million is 6 zeros, thus

$\bf 163,000,000\implies 163\times 10^6 \\\\\\ 93,000,000,000\implies 93\times 10^9\\\\ \cfrac{93\times 10^9}{163\times 10^6}\impliedby \textit{hours per year for one adult} \\\\\\ \cfrac{93\times 10^9\times 10^{-6}}{163}\implie s \cfrac{93\times 10^{9-6}}{163}\implies \cfrac{93\times 10^3}{163}$

that's how many hours each adult spent a year... now, how many hours is that per day? well, there are 365 days a year, so, we simply divide it by 365

$\bf \cfrac{\frac{93\times 10^3}{163}}{365}\implies \cfrac{\frac{93\times 10^3}{163}}{\frac{365}{1}}\implies \cfrac{93\times 10^3}{163}\cdot \cfrac{1}{365}\implies \cfrac{93\times 10^3}{163\cdot 365}\quad \cfrac{hours}{day}$