Expert: Josh - 3/23/2008

Question
underline the key pieces of information contained in the probelem statement.

Answer
Sera, I can't help unless you explain what you need help with.

This question cannot be answered properly without knowing the problem statement. You should include this in the question.

You need to identify "key pieces of information", i.e., information or numbers relevant to the problem you are trying to solve. To do this, you need to have a clear understanding of what you have been asked to solve.

Typically, the story line and names of people are not vital pieces of information. Although it varies from case to case, usually the numbers represent key pieces of information.

e.g. 1, Sam and Tara are contesting in a game of memory. There are twenty words to be remembered. On average, Sam can correctly remember five words every fifteen seconds, while Tara can remember sixteen words in a minute. Who would be the first person to successfully remember (or recall) all twenty words?

Now, the names "Sam" and "Tara" are not critical information. We could have called them person A and B without changing the situation. It also doesn't matter what game or event they participate in. In fact, we can reword this using the same data, turning this into a new situation. But the technique for solving this problem is still the same.

e.g. 2, Steve and Tania are drilling a concrete slab that has a thickness of 20 inches. On average, the drill used by Steve can penetrate 5 inches every fifteen seconds, while the one used by Tania can cut through 16 inches in a minute. Who would be the first person to complete the task?

See, the key pieces of information are still the same.
We associate the numbers with the following:

S (Sam):   memory rate 5 words/15 seconds.
T (Tara):  memory rate 16 words/minute, OR 16 words/60 seconds.

S (Steve): work rate 5 inches/15 seconds.
T (Tania): work rate 16 inches/minute, OR 16 inches/60 seconds.

The key figures are still 5/15 for S, and 16/60 or 4/15 for T.
Whichever problem you look at (game of memory, or drilling) person S completes the job faster. S works at a rate of 5/15, whereas T works at a rate of 4/15 (less than 5/15). These are the things you should highlight and pay attention to.

The amount of work to complete is also important. In example 1, 20 represents 20 "words". In example 2, 20 represents 20 "inches".

Finally, solving the problem. S will take 20/(5/15)=60 seconds to finish the task (in both examples). For T, she will take 20/(4/15)=75 seconds. Therefore, S will finish first.