Question

joan works on commission for a furniture store. she gets a base pay of $80 a day plus 5 percent of the value of any merchandise she sells that exceeds a total of $400. Joan wrote the expression 400 + 0.05 (t - 80), where t represents her sales total in dollars, to compute the total amount of money that she will make. For sales of $475 Joan calculated that she will make $419.75. Explain Joan's error.

Answer 1

We are given the statement:

She gets a base pay of $80 a day plus 5 percent of the value of any merchandise she sells that exceeds a total of $400

 

Then we are given the equation:

Earnings = 400 + 0.05 (t – 80)

 

Now if we read the statement carefully, we can understand that the base pay is $80 and NOT $400. Therefore it should be the constant value in the equation. Now the statement also tells that what will be added to her pay is anything beyond 400, therefore it should be the one inside the parenthesis. That is:

Earnings = 80 + 0.05 (t – 400)                       ---> correct equation

 

Now we use the corrected equation to solve for the earnings when t = 475

 

Earnings = 80 + 0.05 (475 – 400)

Earnings = 83.75 dollars