The difference between the initial temperature and the temperature after an hour is an increase of 5 degrees. Since we need to calculate the time it would take for the temperature to rise to 60 degrees we need to find the difference in degrees from the current temperature to 60 degrees.
60 - 45 = 15 degrees
Since 1 hour equals an increase of 5 degrees we need to divide 15 by 5 to calculate how many hours before the temperature increases to 60 degrees
Step-by-step explanation: the two length 20 and 28 have a close range of value. So the next close range of value is the 38 inch which will make a perfect fit.
Note this rule is by trial and error method and no formula is behind it.