posted by barbie .
summer graded 25 math papers in 30 minutes.larry graded 22 papers in 20 minutes.what is the difference in the number of papers they can grade in two hours?
If Summer grades 25 papers in 30 minutes, and there are 4 half-hours in two hours, multiply 25x4= 100. Summer can grade 100 math papers in 2 hours.
Larry can grade 22 papers in 20 minutes. 60 minutes (one hour) is three times twenty minutes, so two hours is six (doubling the three) multiplied by twenty minutes. So, since 6x20minutes= 2 hours, and he grades 22 papers in 20 minutes, multiply the 22 papers by six for his total. 22x6= 132 papers in 2 hours.
In two hours, Summer grades 100 papers, and Larry grades 132. Therefore, Larry grades 32 papers more in a two hour period of time.