Thursday, August 30, 2012

Tiling

The end of our SAT prep...the most challenging I think...but since you're not 16 anymore, and you've probably tiled a bathroom or bought a rug or put up wallpaper, it may be a snap!

What is the minimum number of rectangular tiles, 12" x 18" needed to completely cover five flat rectangular surfaces, each 60" x 180"?
a)50 b)100 c)150 d)200 e)250 Hints and answer below.

Vacation week continues on the east coast. Here is a beautiful bridge that we traveled over. Just a gorgeous and stunning engineering feat. We are getting a little bit of the tail end of Isaac, too. Last year I was in my first gas line, trying to get off of the Atlantic coast as Hurricane Irene came north. After over an hour we were able to get gas and proceeded out of town for the weekend---returning in a couple days.

This year it is another "I" hurricane and this one brought me my first experience of rain that came so fast and furious that whole streets were impassable and large pools of water developed everywhere. We've had flash floods in Erie, of course, but they are nothing like the coast lands get. Must be very scary in the Gulf towns today. The high tide/water/waves just keep coming and coming and coming.



Now back to our tile problem. Here are some hints/help I would give: Draw a large rectangle and label it 60" on the side and 180" for the length. Then draw a few tiny 12" x 18" boxes in it until you catch on to how many fill a width and maybe even a length.

Another way to think about it is with the formula for the area of a rectangle which most kids know by heart A=LW. The big rectangle has an area of 10,800 and the tiny tiles each have an area of 216. Dividing gives you 50 little ones to fill the larger one. Notice that one of the answers is 50, although that is wrong unfortunately!



A huge thing to master on these "tricky" standard tests is to remember to go back and read the question---because 90% of the time after you've done some calculations you've forgotten what they asked! And in multiple choice questions they always have the most popular wrong answer included. This one asks the number of tiles to cover FIVE surfaces, not just ONE...tricky, yes...very! So the answer is e.

A friend who thinks she's terrible in math wants me to stop these, so this is the last---for now. Who knows, if I find an exciting or interesting one I may pop it in anytime!