Matrix Operations Made Eas[y](ier than necessary), or Always Read the Whole Question

So, last semester I took MAT187, Precalculus. The course was conducted using MathXL, which is produced by Pearson.

I think it’s safe to talk about this now that I’ve finished the class and I have my passing grade.

This was an actual test question the chapter quiz on matrix operations. I copied it verbatim when I took the test, but I’m having a little trouble with the table formatting on LJ.

The table shows the cost per serving, in cents, for items on a hospital menu. A dietician orders 63 meals from menu 1, 48 meals from menu 2, 99 meals from menu 3, and 59 meals from menu 4.

MENU

MEAT

POTATO

VEGETABLE

SALAD

DESERT

1

44.3

6.4

10.7

7.5

8.9

2

53.5

4.2

9.3

6.5

12.1

3

46.4

8.1

12.3

8.7

9.2

4

51.7

7.8

11.7

9.7

10.2

a) Complete Matrix M that represents the data in the table.

M=

______

6.4

10.7

7.5

8.9

53.5

4.2

9.3

6.5

12.1

46.4

8.1

12.3

_____

9.2

51.7

7.8

11.7

9.7

10.2





b) Complete the row matrix N that represents the amount ordered from each menu.

N= [ ___ 48 ___ 59 ]

c) Complete the product NM.

NM= [ _____1886.9 3028.5 22181.1 ________ ]

d) Complete the entry representation.

The total cost for meat is 13002.8 cents, for potatoes is __________ cents, for vegetables is 3028.5 cents, for salads is __________ cents, and for deserts is 2654.1 cents.

Don’t start furiously typing numbers into Excel or your trusty TI-84 Plus Silver Edition just yet. Just read the whole problem. This is sort of one of those “When you see it, you’ll shit bricks” moments.

Wait for it.

You see, every answer is in the question.

a) is answered by the table in the problem description.

b) is answered by the problem description itself.

c) is answered by (d), and

d) is answered by (c).

I’m not sure if the test writer was just trying to see if we were paying attention, or if they really bungled it this badly. I’d love to know how many people get this wrong. And since we could take the same quiz as many times as we needed to pass, I’d really love to know how many people got it wrong more than once.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s