Question 1122630: I have won the right to build a swimming pool. The pool measures 50 metres in length, 25 metres in width and 2 metres in depth at the shallow end, sloping down (linearly) to 6 metres in depth at the other.
Using the pool measurements above, how many 50mm x 50mm tiles (margin for cement/grouting already included) will be needed, assuming an additional 10% allowance is required for wastage (to the nearest thousand)?
Options are -816,000; -742,000; -75,000; -8,000
Thanks
Answer by greenestamps(13200)   (Show Source):
You can put this solution on YOUR website!
Since this is multiple choice, it apparently is not a real world question but rather a problem for a math assignment. In that case, you can do the work to find the answer.
There are 5 surfaces to cover: 2 sides; shallow and deep ends; and the bottom of the pool.
(1) Each side is a trapezoid with bases 2 and 6 and height 25; the area of a trapezoid is the height times the average of the bases.
(2) The shallow end is a rectangle 25x2; the deep end is a rectangle 25x6; I assume you know the formula for the area of a rectangle.
(3) The bottom of the pool is a bit longer than 50m because of the slant. However, since we are estimating to the nearest thousand and adding 10% for wastage, we can consider it to be a 50x25 rectangle.
The square tiles are 50mm on a side, which is (1/20) meter; so it takes 20*20=400 tiles to cover a square meter.
Figure the total surface area to be covered, multiply by 400 to get the number of tiles, and then add the extra 10%.
One of the answer choices is correct. You will note that 2 of the 4 answer choices are not even the right order of magnitude.
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