Keep track of units. The math will be easier to compute if the numbers are put into scientific notation.
B
b
Keep track of units. To convert the units of hours per year to hours per week, use the fact that there are 52 weeks in a year.
A
a
Approximately 1636 hours per year
B
b
Approximately 31 hours per week
Practice makes perfect
a
We are trying to find the amount of hours each adult watched television in a year. We will divide the total hours adults spent watching television in one year by the amount of adults, and we will get an answer with the units of hours per year per adult.
Hours adults spent watching television per year/Amount of adults= 342billion hoursyear/209million adultsIt will be easiest to divide these numbers if they are in scientific notation. Notice that 342 billion can be written as 342 000 000 000. That is, 342.0 * 10^9. Now, to finish putting this in scientific notation we need to shift the decimal two points over.
342.0 * 10^9 ⇒ 3.420 * 10^(11)
Now, let's put 209 million in scientific notation. This can be written as 209 000 000. That is, 209.0 * 10^6. To finish putting this in scientifc notation we need to shift the decimal two points over.
209.0 * 10^6 ⇒ 2.090 * 10^8
Now that our numbers are in scientific notation, we can divide them.
We have found that each adult spent approximately 1636 hours that year watching television.
b
Now, we need to convert this to the units of hours per week.
hours/year ⇒ hours/week
Note that there are 52 weeks in a year, so to convert to the units of hours per week we need to divide 1636 by 52 weeks per one year.
1636 hours/year * 1 year/52weeks ≈ 31 hours/week
We have found that each adult spent approximately 31 hours per week watching television over the duration of a year.
