document.write( "Question 447437: Not sure exactly which category this goes under. I have a very long math problem I'm struggling to solve. I've googled and seen parts of it or similar problems, but I haven't seen the full thing, so I'm not entirely sure how to go about solving this. Any help will be appreciated, so I thank you in advance. I will also post the parts I think I already worked out so that you can see what I've done so far.\r
\n" ); document.write( "\n" ); document.write( "A gardener has a rose garden that measures 30 feet by 20 feet. He wants to put a uniform border of pine bark around the outside of the garden. Let x be the width of the border in feet. Write an expression for the total area of the border in terms of the width x.
\n" ); document.write( "I came up with 4x^2 + 100x as my answer. Correct?\r
\n" ); document.write( "\n" ); document.write( "Find out how wide the border should be if he has enough pine bark to cover 336 square feet.
\n" ); document.write( "I came up with 3 feet as my answer. Correct?\r
\n" ); document.write( "\n" ); document.write( "If the border needs to be covered to a depth of 3 inches and pine bark costs $29 per cubic yard, what will the material cost to lay the pine bark border? Assume that you must purchase a whole number of cubic yards and not a fraction of a cubic yard.
\n" ); document.write( "Here's where I'm struggling with *how* to answer this one. I came up with $6786, but I'm thinking that's way off. Any advice or suggestions?\r
\n" ); document.write( "\n" ); document.write( "Also, now assume you can actually buy as much or as little bark as you need to cover the border area, that is, the vendor will sell even a small fraction of a cubic yard if you want. Write an expression for the cost in dollars as a function of the width x, of the border in feet. Assume again that the border is to be covered to a depth of 3 inches and that pine bark costs $29 per cubic yard.
\n" ); document.write( "Please help! :) Thanks!\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(There are actually two more questions to this problem, but I'm hoping the above, when I'm able to figure it out, will help me in solving them.)
\n" ); document.write( "

Algebra.Com's Answer #308023 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
A gardener has a rose garden that measures 30 feet by 20 feet.
\n" ); document.write( "He wants to put a uniform border of pine bark around the outside of the garden. Let x be the width of the border in feet.
\n" ); document.write( "Write an expression for the total area of the border in terms of the width x.
\n" ); document.write( "I came up with 4x^2 + 100x as my answer. Correct?
\n" ); document.write( "-----
\n" ); document.write( "Draw the picture:
\n" ); document.write( "You have a rectangle inside a rectangle.
\n" ); document.write( "The area of the larger rectangle is (30+2x)(20+2x)
\n" ); document.write( "The area of the inside rectangle is 30*20
\n" ); document.write( "So the area of the border is (30+2x)(20+2x)-30*20 = 4x^2+100x sq. ft.
\n" ); document.write( "-------------------------------------------------------------------------------
\n" ); document.write( "Find out how wide the border should be if he has enough pine bark to cover 336 square feet.
\n" ); document.write( "I came up with 3 feet as my answer. Correct?
\n" ); document.write( "---
\n" ); document.write( "Solve 4x^2+100x = 336
\n" ); document.write( "x^2+25x-84 = 0
\n" ); document.write( "(x-3)(x+28) = 0
\n" ); document.write( "Positive solution:
\n" ); document.write( "x = 3 ft.
\n" ); document.write( "====================
\n" ); document.write( "If the border needs to be covered to a depth of 3 inches and pine bark costs $29 per cubic yard, what will the material cost to lay the pine bark border? Assume that you must purchase a whole number of cubic yards and not a fraction of a cubic yard.
\n" ); document.write( "Volume = (area)(depth) = 336 sq.ft * (0.25 ft) = 84 cu. ft
\n" ); document.write( "84 cu ft = 84/27 = 3.111 cu yrd
\n" ); document.write( "Price = 3.1111*$29 = $90.22
\n" ); document.write( "=============================
\n" ); document.write( "===============================
\n" ); document.write( "Also, now assume you can actually buy as much or as little bark as you need to cover the border area, that is, the vendor will sell even a small fraction of a cubic yard if you want. Write an expression for the cost in dollars as a function of the width x, of the border in feet. Assume again that the border is to be covered to a depth of 3 inches and that pine bark costs $29 per cubic yard.
\n" ); document.write( "----------------------
\n" ); document.write( "Volume = (area)(depth)
\n" ); document.write( "Volume = [(4x^2+100x)(1/4)]/27 = (27/4)(4x^2+100x) cu. yds
\n" ); document.write( "---
\n" ); document.write( "Cost = (29*27/4)(4x^2-100x) = 195.75*4(x^2-25x) = 783(x^2-25x) dollars
\n" ); document.write( "=========================================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( "
\n" ); document.write( "
\n" );