Question

Topsoil A 40-pound bag of topsoil will cover a surface area of 12 ft2.
a) How many pounds of topsoil are needed to cover a surface area of 480 ft2 ?

b) How many bag of topsoil must be purchased to cover a surface area of 480 ft2 ?

Answer 1

\[\frac{ 480~ft^2 }{ 1 }*\frac{ 40~lb }{ 12~ft^2 } = ? ~lb\]

Answer 2

ft^2 cancels, you are left with pounds of soil

Answer 3

Then use that answer from part a) in this for part b

\[\frac{ ?~pounds }{ 1 } * \frac{ 1~Bag }{ 40~lb } =~~ ? ~~Bag\]

Answer 4

i got for a 1600

Answer 5

1600 pounds

Answer 6

right

Answer 7

and for b is 40

Answer 8

You see how i set it up, you just start with what you are given, then multiply by ratios of 1 to cancel units in your favor,
Like in part a, you start with 480 ft^2
Then multiply it by a ratio of 1, 40 lb = 12 ft^2 , you want the f^2 to cancel, so you put it in the bottom

Answer 9

Then for part b , you use 40 lb = 1 bag

Answer 10

yes i want to know how u set it up from the word problem

Answer 11

You can always multiply by fractions that equal 1, like \[\frac{ 1~bag }{ 40~lb }\]
they told you 1 bag is 40 lb

Answer 12

worry about the units first, arrange the problem so the units cancel out , then take care of the numbers

Answer 13

Given: 1600 lb, convert to bags
\[\frac{ 1600~lb }{ 1 } * \frac{ 1~Bag }{ 40~lb } =~~ ? ~~Bag\]

Answer 14

1 bag = 40 lb, put lb in the bottom , so lb cancels from top and bottom, you are left with bags

Answer 15

Just remember to get the units to work out first

Answer 16

that make it a bit easier?

Answer 17

yes