Math Stories for the Everyday




My son and daughter-in-law moved to a new home last weekend.  For a housewarming gift my husband and I decided to surprise them with a portable dishwasher.  Having a dishwasher was high on their wish list but this home does not have one.

I researched dishwashers on the internet.  The kitchen does not have room for a built in.  The two options available are a small counter top model or a full sized portable. This is a family of 4 so the small countertop model would not be practical. It only fits 6 place settings at a time. The other negative issue is it would sit on the countertop.  My daughter-in-law likes to decorate cakes as a side business and needs all the countertop space possible.  The full sized portable model is the best option.  The full sized model will hold 14 place settings.  There is an ideal area in the attached dining room to store the dishwasher when not in use.  It will actually hide the hook ups to a stackable washer/dryer that used to be in the space.


We visited two stores and had one model to choose from at each store.  Following is a chart I kept while comparison shopping.




Miles Maytag




List Price



Repeat customer discount









Total Price



Price after Rebate



We decided to purchase the model from Miles Maytag because it was cheaper and we like to buy local.


Portable dishwashers are more expensive than built in models.  I asked the salesman why.  I thought he would say it’s because the sides and top are finished.  He explained it only costs them about $8 on the extra finishes.  The main reason is supply and demand.  There is little demand for these dishwashers and it is expensive to keep the assembly line open and running.


My husband and I bought a dishwasher for our home early in Jan.  It was a Maytag and cost $477.77.  I decided to calculate the percent of change.  Original (built in) cost $477.77.  New (portable) cost 614.79. 

First I determined the difference:  614.79 – 477.77 = 137.02

Next I applied the percent proportion.  P = r

                                                              B    100 

137.02 = r__             Cross multiply:   13702 = 477.77r

477.77    100        Divide each side by 477.77:     28.679071 = r

The portable dishwasher was a 29% increase over the built in.


The last thing I am curious about is volume of the countertop model vs. the full sized portable.  Here’s a chart of the measurements.  (Can you tell I like charts?)  I will use the formula: V = lwh




Counter top

Full size

Height in inches



Length in inches



Width in inches



Area in cubic inches











2 responses »

  1. Recently, I used the percent difference to illustrate how much money could be saved by going to college in one’s home state. I showed my cousin that the current out-of-state tuition at Rutgers University is 29% higher than the in-state tuition. I think I proved my pointed, especially when I mentioned that the student loans kick in 6 months after graduation, and that I still owe $17,000 after graduating in 1994.

  2. Hey I shop at miles too. The best thing is they make service calls quickly. Especially if you bought it from them. I don’t know anything about the repeat buyer discount. Did you know that there is something called an apartment size d.w.. I found out about it when we went to the direct buy sales pitch. They wanted $5000. to join and then there was a yearly fee of a couple hundred I think. But we never spend $5000s on a home project ,so you weren’t really saving anything until you reached that amount. Plus if I gave them my $5000,I wouldn’t have any money left to spend.

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