Jason W.

asked • 07/30/15

A pane of glass is 22 in * 35 in * .167 in thick. It is shattered into square pieces...

A pane of glass is 22 in * 35 in * .167 in thick. It is shattered into square pieces .125 in on a side .What is the percent increase in total surface area of glass?
 
I keep getting 2.96*102 percent increase, but the answer is 2.63 * 102 percent increase. I found the original SA(1559.038), then the original volume. I divided the volume by the volume of 1 little piece, and found how many little pieces formed. Then I found the SA of each little piece, and multiplied by the amount of pieces. Then I used the percent difference formula, and got my answer, which is not the right answer. Please help.

Mark M.

You were on the correct tack. Some of the pieces, those from the edge of the original piece contribute only 3 new edges. The four pieces from the corners only contribute 2 new edges.
 
Suggest you draw a picture to visualize which pieces contribute to addition SA.
 
Also you mixed volume with SA.
 
Keep up the good work!
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07/30/15

1 Expert Answer

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Meira P. answered • 08/02/15

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22 in * 35 in * .167 in thick. It is shattered into square pieces .125 in on a side .What is the percent increase?
 
Step 1) The surface are of the original is (22*35)*2 + (22*.167)*2 + (35*.167)*2 = 1559.04
Step 2) If it is shattered into square pieces, .125 pieces on a side... which side of the piece of glass gets the .125? This could potentially be (.167 / .125) squares with surface area {[(.125)^2] + (22*35)*2 + (35*.167)*2}  ... or two other similar equations. What step two equations did you use and why?
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