SOLUTION: please answer my question: Suppose you have 10 kg of cement, 5 kg of gravel, and 5 kg of sand for making concrete. Your concrete should contain 25% water by mass. How much water

Question 164585: please answer my question:
Suppose you have 10 kg of cement, 5 kg of gravel, and 5 kg of sand for making concrete. Your concrete should contain 25% water by mass. How much water should you add?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let x=amount of water needed
Total weight of the mixture=10+5+5+x=20+x
And we are told that the water equals 25% of the mixture, so:
0.25(20+x)=x get rid of parens (distributive law)
5+0.25x=x subtract 0.25x from each isde
5+0.25x-0.25x=x-0.25x collect like terms
5=0.75x divide each side by 0.75
x= 6.6667 or 6 2/3 kg----------------------amount of water needed
CK
20+6.6667=26.6667
0.25*26.66667= 6.6667
6.6667=6.6667
Hope this helps---ptaylor
RELATED QUESTIONS
A mixture contains 10 kg of sand, 20kg of cement and 5 kg of gravel. Find the ratio of... (answered by josgarithmetic)

The ratio of sand to cement is 6 to 5. How much cement is in 220 kg mixture? (answered by ewatrrr)

the ratio of sand to cement is 6 to 5. how much cement is in a 220 kg... (answered by Fombitz)

a certain concrete mixture contains 6.00% cement and 8.00% sand how many kilograms of... (answered by josgarithmetic,ankor@dixie-net.com,ikleyn)

A cement mixture with 27% sand is created using 10.5 kg of sand. What is the mass of the... (answered by stanbon)

2. A mixture contains 6 kg sand and 4 kg of cement. How much cement must be added to kema (answered by harpazo)

please solve this problem. A certain concrete mixture contains 6.00% cement and 8.00% (answered by josgarithmetic)

4 shovels of sand are used for every 5 shovels of gravel in making cement. How many... (answered by vidhyak)

I am having trouble setting up my systematic equation in this word problem. "a... (answered by ankor@dixie-net.com)