Question

`8.99*10^9` seconds is how many years?

Answer 1

`"285 years"`

Explanation:

Your strategy here will be to use a series of conversion factors to take you from

• seconds to minutes

`"1 minute " = " 60s seconds"`

• minutes to hours

`"1 hour " = " 60 minutes"`

• hours to days

`"1 day " = " 24 hours"`

• days to years

`"1 year " = " 365.25 days"`

The last conversion factor doesn't use a whole number because once every `4` years we have what is called a leap year, which means that instead of `365` days, the number of days we have in a regular year, we get `366` days.

So, use the conversion factors to find

`8.99 * 10^9 color(red)(cancel(color(black)("s"))) * (1color(red)(cancel(color(black)("min"))))/(60color(red)(cancel(color(black)("s")))) * (1color(red)(cancel(color(black)("hr"))))/(60color(red)(cancel(color(black)("min")))) * (1 color(red)(cancel(color(black)("day"))))/(24color(red)(cancel(color(black)("hr")))) * "1 year"/(365.25color(red)(cancel(color(black)("days"))))`

`=2.85 * 10^2"years" = "285 years"`

The answer is rounded to three sig figs, the number of sig figs you have for `8.99 * 10^9` seconds.