So, she has 3hrs to grade all papers, for 35 students.. alrite.
the first 5, she does them in 30minutes.. what's the speed rate? well, 5/30 or 1/6
now, she has still 2 hours and a half, or 150 minutes, to do the remaining 30 papers... she has to work at a rate of 30/150 then... which is 1/5 simplified.
now if we take 1/6 as the 100%, what is 1/5 in percentage then?
so 1/5 is 120% in relation to 1/6... meaning the rate of 1/5 she needs to move through, namely 1 paper every 5 minutes, is 20% faster than 1/6.
the first 5, she does them in 30minutes.. what's the speed rate? well, 5/30 or 1/6
now, she has still 2 hours and a half, or 150 minutes, to do the remaining 30 papers... she has to work at a rate of 30/150 then... which is 1/5 simplified.
now if we take 1/6 as the 100%, what is 1/5 in percentage then?
so 1/5 is 120% in relation to 1/6... meaning the rate of 1/5 she needs to move through, namely 1 paper every 5 minutes, is 20% faster than 1/6.