Question

George told his teacher that he spent over 21,000 seconds working on his homework. Part A: Express this amount using scientific notation. Part B: What would be a more appropriate unit of time for George to use? Explain and convert to your new units.

Answer 1

Part A:

To write the number in scientific notation, remember to add one unit to the exponent of the base 10 for each place that the decimal point has been moved to the left:

`\begin{gathered} 21,000=21,000*10^0 \\ =2.1*10^4 \end{gathered}`

Part B:

Since one minute has 60 seconds, divide 21,000 by 60 to find the time in minutes:

`(21000)/(60)=350`

Since one hour has 60 minutes, divide 350 over 60 to find the time in hours:

`(350)/(60)=5.833\ldots`

Find what 5 hours is equal to in minutes, so we can express the result as 5 hours + remaining minutes:

`5*60=300`

Find the difference from 350 minutes to 300 minutes: