Math Help

Archive for June, 2008

like a rose by cj_angeline21

Question: 7th Grade Math Homework Help!?

OK i have three questions I’m so confused about:

Answer: 1.The length and breadth of Rectangle A are in the ratio 3:2. The length and breadth of Rectangle B are in the ratio 5:3. If the perimeters of rectangles A and B are in the ratio 5:4, find the ratio of the area of rectangle A to B.

I’ll use capital letters for triangle A and lowercase for triangle B
L = (3/2) W
A = L*W = (3/2)W^2
P = 2(L+W) = 2( (3/2)W + W) ) = 5W

l = (5/3)w
a = l * w = (5/3)w^2
p = 2(l+w) = 2 ( (5/3)w + w) = (13/3)w

P/p = (5/4) = [5W] / [(13/3)w] = (15/13)(W/w)
W/w = (5/4) (13/15) = 13/12

A/a = [(3/2)W^2] / [(5/3)w^2]
A/a = (9/5) (W/w) (W/w) = (9/5) (13/15) (13/15) = 1521/1125 = 1.352

2.Grade A tea costs 10% more than grade B tea and grade B costs 10% more than grade C tea.
(a)By what percentage does Grade A tea cost more than grade C tea?

A = B (1.1)
B = C (1.1)
A = C (1.1) (1.1) = C (1.21)
A/C = 1.21 or A costs 21% more than C

(b)By what percentage does Grade C tea cost less than Grade A tea?

C/A = 1 / 1.21 = 0.826 or C costs 17.4% less than A

3.Every year the monthly rent for a shop increases by 10%. The shopkeeper finds that he has to pay $168 more per month than he did two years ago. Find his present rent per month.

R = (R-168) (1.1) (1.1)
R = (1.21)R – (168)(1.21)
(0.21)R = 203.28
R = 203.28/(0.21) = $968

3rd Grade Math Lesson

Question: Where do I find a really good Geometry homework helper?

I need a REALLY REALLY Good Sign-up FREE Math (Geometry Preferably) homework helper site. Quick.

Answer: Webmath.com has a Geometry section.

http://www.webmath.com/index5.html

Also try Math.com

http://www.math.com/homeworkhelp/Geometry.html

http://www.onlinemathlearning.com/geometry-help.html

Pre-Algebra and Trigonometry Homework Help: Free Math Tutorials