A cross-section of a standard or nominal "two by four" board actually measures 1 1/2 inch by 3 1/2 inch. the rough board is 2 inches by 4 inches but is planed and dried to the finished size. What percent of the wood is removed by planing and drying? OK so the answer is 34.375% but HOW step by step did you come up with the answer? I really have no clue!??
2007-09-18 13:33:37 · 8 answers · asked by frogbfound 4 in Science & Mathematics ➔ Mathematics
Imagine that you're looking at the end of a long board.
It looks like a rectangle, right?
Suppose the rectangle of a board is 2 x 4.
Then you cut the board so that it's 1.5 x 3.5.
How much did you cut off?
Well, what I would do is calculate the area before and after.
BEFORE = 2 x 4 = 8.
AFTER = 1.5 x 3.5 = 5.25.
So, how much did you cut OFF?
8 - 5.25 = 2.75.
So now you need to find out the answer to this:
"2.75 is what fraction of 8?"
2.75 = 8x
x = 0.34375
Multiply by 100 to get it in percentage form.
0.34375 x 100 = 34.375%
2007-09-18 13:41:30 · answer #1 · answered by PJ 3 · 3⤊ 0⤋
A percentage is really a ratio. What you want to do is set up a ratio between the difference of the two areas, and the unfinished area.
The area of the finished board is 3.5 inches by 1.5 inches which is 3.5 * 1.5 = 5.25 sq. in.
The area of the unfinished board is 4 inches by 2 inches
which is 4 * 2 = 8 sq. in.
(8 - 5.25) / 8 = X / 100
2.75 / 8 = X / 100
275 / 8 = X
X = 34.375 %
Cheers!
2007-09-18 20:43:15 · answer #2 · answered by gitter1226 5 · 1⤊ 0⤋
1.5 is 75% of 2
3.5 is 87.5 % of 4
So new cross-section is .875*.75= .65625 of old cross section.
So loss =1-.65625= .34375 = 34.375%.
2007-09-18 20:42:58 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋
2x4 has an area of 8.
1.5x3.5 has an area of 5.25.
(8-5.25)/8 * 100% = 34.375%
.
2007-09-18 20:38:27 · answer #4 · answered by Anonymous · 1⤊ 1⤋
you really should do your OWN homework. If you need help ask a parent or teacher. Cheaters never win or LEARN!
2007-09-18 20:40:12 · answer #5 · answered by ANGEL Baby 3 · 0⤊ 2⤋
When you dry it, you're removing water, not wood. Keep that in mind.
2007-09-18 20:39:37 · answer #6 · answered by Anonymous · 0⤊ 3⤋
uhhh i dont really know but wait ..... i got nothing sorry... easy points right :P
2007-09-18 20:40:16 · answer #7 · answered by yessica_reynoso1@yahoo.com 1 · 0⤊ 2⤋
SRRY IDK. i suck at math
2007-09-18 20:38:14 · answer #8 · answered by afi_punkie 1 · 0⤊ 4⤋