I need help with 8th grade math probs.

[3girls2luv]

I am helping dd1 with word problems and I am stuck. I am no way a math wiz so I need some help. This is the problem:

Mr. Grove would like to plant grass seeds in his back yard shaped as a trapezoid. The seed cost $7.45 a pound and will cover 105 sq.ft. If the trapezoid bases are 125 and 187 feet, and the perpendicular distance between the bases is the average of the two bases. What will be the total cost for the grass seed?

I am not sure how to figure out the perpendicular distance. TIA

[mtmomma]

This is really when Rod needs to chime in ;-)

[hidesome]

Off the top of my head, I think the answer is [(125+187)/2 x (125 + (187-125)] x 7.45/105

[billysmom]

I found the equation for area of a trapezoid on this website: http://www.mathgoodies.com/lessons/vol1/area_trapezoid.html

To find the area, you add the two bases, multiply by the height, and divide by 2. You already have the two bases, and to find the height, you average both of them. (125+187)/2 = 156.

The area then, is: add the two bases (125 + 187 = 312) multiply by the height (312 x 156 = 48,672) and divide by 2 (48,672 / 2) = 24,336.

To find out how much seed you need, take the area and divide by the area each bag covers: 24,336 / 105 = 231.77 (rounded), which means you need 232 bags of seed. 232 bags x $ 7.45 = $1,728.40

I'm pretty sure that's right. Hope it helps.

[3girls2luv]

Ok I think thats it. $33.53

[3girls2luv]

Oh man that looks better I was totally wrong.

[3girls2luv]

I hate word problems!!!! Obviously I am not good at them...lol. Thanks for your help!

[billysmom]

You're welcome. I love word problems. I always did them first!

[catkrazy99]

Sorry, but i'm having difficulty with first grade math word problems. Apparently I wasn't the only one, though, so that makes me feel a bit better.

[billysmom]

Sorry, but i'm having difficulty with first grade math word problems. Apparently I wasn't the only one, though, so that makes me feel a bit better.

I can do math, but I'm up a creek when it comes to history help. I'm horrible at history.

[haleysmom]

Can you guess who always helped me with my homework? ;)

[hotlama]

$1,726.70

[haleysmom]

When Haley was born it was already decided that any homework questions she gets when she is older will be called into "Aunt Billysmom"

:p

[3girls2luv]

There was one word problem that I seriously think it had to be a typo cuz it was pretty much worded the same except the numbers where a little different and the end question was "how much would the paint cost?" I was confused cuz the man was planting grass not painting.

[_MrsC_]

That's some expensive grass.

[3girls2luv]

Yeah I thought so too but that formula that billysmom gave me was off the website we were looking at lastnight. We shall see what the teacher says today.