When asked for an answer that is to be rounded, remember to round as the last step of the problem. In other words, when completing your calculations, always use the numbers given in the problem as is. Then after you have the answer, round it.
In this problem you are asked to calculate how much faster Willie's
time was than Erv's time. To complete the problem, find the difference in the
two runners' times.
13.27 - 12.91 = 0.36
The second answer (0.36) is wrong because the answer has not been
rounded to the nearest tenth.
Now let's try another one.
It takes 12.36 ounces of gasoline to fill a certain container. If you have 239 containers, how many ounces to the nearest tenth will be needed to fill all the containers?