Problems with Writing Answer (Part 4)

Here are a few common mistakes that are made on Part 4 of the word problems. Check them out and avoid them :)

• Not writing the answer out in a complete sentence: There are lots of variations on this mistake. To keep yourself straight, just remember that a word problem needs a word answer. Sometimes because of time, I see people simply copy there answer from Part 3. E.g. x=3, or x is 3. Remember, part 4 shouldn't have any variables in it, just words. Also I get some single number answers like 3. There is no explanation what the number is supposed to mean. Give me a nice complete sentence.

• Not answering the whole question: A lot of times the word problem asks for more than one quantity, but in our equation we only have one variable. Sometimes only the quantity that the variable represents makes it into the student's answer in part 4. It looks something like this.
• Question: Anna, Lea, and Simon have ages that add up to be 78. If they were all born in consecutive years, how old is each one?
• Part 1-- x: the youngest child
• Part 2--  x + (x+1)  + (x+2) = 78
• Part 3--  x=25
• Part 4-- The youngest one is 25.

Everything is great except for Part 4. Make sure that you include all the info the question is asking for. A full credit answer would be Anna, Lea, and Simon are 25, 26, and 27. 

• Not interpreting negative solutions from Part 3 correctly: This is a problem in Intermediate Algebra from Ch 5.9 on. Sometimes there are two solutions in Part 3, often a positive and negative one. Sometimes we can interpret the negative solution, sometimes we can't. Here's an example where the student doesn't realize that he/she can interpret it, which would give two solutions in Part 4. The question is What two consecutive even numbers have a product of 440?

The student got x = 20 and x = -22 in part 3, which is right. If 20 is the first integer, 22 is the second integer. If x = -22, then the next integer is -20. Since x is defined as an integer and integers can be negative numbers, it makes sense to interpret x = -22 into our answer for part 4. A nice Part 4 might be...There are two pairs of consecutive even integers that multiply to be 400. First the pair 20 and 22, and second the pair -22 and -20.

• Interpreting inequality answers as equalities. In Ch 2.8 in particular, MyMathLab asks a lot of questions involving inequalities. Key phrases in those kind a word problems are "more than", "at least as many".... A lot of times students set up an equality instead of an inequality. I understand this. Equalities are better understood and Ch 2.8 comes after Ch 2.6, the equality chapter. Bottom line, I won't count off if you use an equality in Part 2, but if the question asks for a range of answers, that should be reflected in the way you word your answer in Part 4. Here is an example were the student has missed that nuance.

 Great problem, except Part 4 should read "The length of the base needs to be at least 32 ft."