Elena and osman are measuring the time taken for some ice to melt in different places

playground: 45 minutes 12 seconds
classroom: 28 minutes 43 seconds
corridor: 33 minutes 27 seconds

in minutes and seconds, what is the difference in the slowest and quickest time taken for the ice to melt

The slowest time it took for ice to melt was on the playground, as it took 45 minutes and 12 seconds.

The fastest time it took for ice to melt was in the classroom, as it took 28 minutes and 43 seconds.

To find the difference between these two amounts, we just subtract the minutes and seconds.

45 minutes 12 seconds - 28 minutes  43 seconds

Well, we could subtract the minutes and seconds separately, but if we attempted to do so right now, we would get a negative number for the seconds, which wouldn't work.  So, we have to convert one of the minutes into seconds.  (1 minute = 60 seconds, so subtract one minute from 45 and add 60 seconds to 12.)

44 minutes and 72 seconds - 28 minutes and 43 seconds 

Now we can just subtract the times separately with minutes and seconds.

44 - 28 = 16 minutes

72 - 43 = 29 seconds

Therefore, the difference in the slowest and quickest time taken for the ice to melt was
16 minutes 29 seconds

30 because 1/5th of an hour is 12 min, 60 divided by 12 is 5, 6 times 5 is 30