I am lost on this word problem. Please help? (:

A certain mix of concrete is composed of 94lb (one sack) of cement, 50 lb of water, 191lb of sand, and 299lb of gravel. The final mix of concrete will weight 151.2 lb/cu.ft. How many sacks of cement will be needed for a wall with a volume of 1760 cu.ft.

Question

I am lost on this word problem. Please help? (:

A certain mix of concrete is composed of 94lb (one sack) of cement, 50 lb of water, 191lb of sand, and 299lb of gravel.  The final mix of concrete will weight 151.2 lb/cu.ft. How many sacks of cement will be needed for a wall with a volume of 1760 cu.ft.

ganeshie8 · Answer

begin with writing down whats given

anonymous · Answer

Okay, I have drawn a visual as well.

ganeshie8 · Answer

good :) 

so the wall has a volume of1760 cu.ft
you want to fill this volume with the concrete mix.

ganeshie8 · Answer

i need paper pen... wait :)

ganeshie8 · Answer

lets find out how much concrete is needed to fill 1760 cu.ft volume of wall

anonymous · Answer

okay

ganeshie8 · Answer

concrete needed for the entire wall = 1760 * 151.2

= ?

anonymous · Answer

=266112

ganeshie8 · Answer

concrete needed for wall = 26612 lb --------------------(1)

ganeshie8 · Answer

keep that aside for a sec

anonymous · Answer

Alright.

ganeshie8 · Answer

94lb (one sack) of cement, 50 lb of water, 191lb of sand, and 299lb of gravel.

ganeshie8 · Answer

add them all

anonymous · Answer

=634

ganeshie8 · Answer

94 + 50 + 191 + 299 = 634 lb of concrete mix

ganeshie8 · Answer

634 lb mix has 1 sack of cement

ganeshie8 · Answer

right ?

anonymous · Answer

I thought 94lb= 1 sack ?

ganeshie8 · Answer

thats correct !

94lb of cement = 1 sack of cement

anonymous · Answer

So is every 94 pounds one sack ?

ganeshie8 · Answer

and in 634 lb of mixture, we have 94 lb of cement

ganeshie8 · Answer

we need to find ONLY cement sacks contained in the entire wall.

ganeshie8 · Answer

fore every 634 lb of mixture, 94 lb of cement is present

ganeshie8 · Answer

in 26612 lb of mixture, how much cement would be present ?

anonymous · Answer

Okay, I understand now. I thought:
634/94=6.7447 sacks

ganeshie8 · Answer

yeah good.... thats wrong as you see it now. that gives total sacks of mixture. but we are looking for cement only here

anonymous · Answer

Okay, I am not sure about the 26612 lb mixture.

ganeshie8 · Answer

so we have,

634 lb contains 1 sack of cement

ganeshie8 · Answer

is that clear upto this poitn ?

anonymous · Answer

Divide?

ganeshie8 · Answer

to find how many sacks of cement present in 26612 lb, you just divide 634 lb

26612 / 634 = ?

anonymous · Answer

=41.9748

anonymous · Answer

in sacks?

ganeshie8 · Answer

im getting 419.7 =  ~ 420 sacks

ganeshie8 · Answer

oops! i was wrong... 41.97 = ~42 sacks is correct !!

anonymous · Answer

Okay

anonymous · Answer

Sorry, but where do I go from  here? @ganeshie8

ganeshie8 · Answer

we are done lol. that wall requires ~42 sacks of cement.

anonymous · Answer

Oh okay haha. Thanks for your help!

ganeshie8 · Answer

np.... yw :)