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Question 321410: 1) A silversmith has two alloys, one containing 30% silver and the other,55%. How much of each should be melted and combined to obtain 100 grams containing 45% silver?
2) A cellular phone company charges customers a certain amount for the first minute of a long distance call and an additional amount for each suceeding ...minute. A customer makes two calls to the same city, a 33-minute call for Php 269 and a 19-minute for Php 157. How much does the cellular phone company charge for the first minute? for each succeding minute?
3) A swimming pool can be filled by three water pipes, A,B and C. Pipe C alone can fill the pool in 8 hours. If pipes B and C are used together, the pool can be filled in 6 hours. If pipes A and B are used together, it takes 10 hours. How long does it take to fill the pool if all three pipes are used?
i need ur help!
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! 1.A silversmith has two alloys, one containing 30% silver and the other, 55%.
How much of each should be melted and combined to obtain 100 grams containing 45% silver?
:
Let x = amt of 55% alloy
Total amt will be 100 gr, therefore
(100-x) = amt of 30% alloy required
A typical mixture equation, using decimals
.55x + .30(100-x) = .45(100)
.55x + 30 - .30x = 45
.55x - .30x = 45 - 30
.25x = 15
x = 
x = 60 gr of 55% alloy
then
100 - 60 = 40 gr of 30% alloy
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2) A cellular phone company charges customers a certain amount for the first
minute of a long distance call and an additional amount for each succeeding minute.
A customer makes two calls to the same city, a 33-minute call for Php 269
and a 19-minute for Php 157.
How much does the cellular phone company charge for the first minute? for each succeeding minute?
:
Let x = amt charged for 1st min
Let y = amt charged for each succeeding min
:
Call 1: x + 32y = 269
Call 2: x + 18y = 157
-----------------------Subtraction eliminates x, find y
" "0x + 14y = 112
y = 
y = 8 cents for each succeeding min
I'll let you find the value of x, the first minute cost
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3) A swimming pool can be filled by three water pipes, A,B and C.
Pipe C alone can fill the pool in 8 hours.
If pipes B and C are used together, the pool can be filled in 6 hours.
If pipes A and B are used together, it takes 10 hours.
How long does it take to fill the pool if all three pipes are used?
:
Let the completed job = 1 (a full pool)
:
"pipes B and C are used together, the pool can be filled in 6 hours."
 +  = 1
It tells us pipe C can do it in 8 hrs, therefore:
+  = 1
multiply by 8B
8(6) + 6B = 8B
48 = 8B - 6B
48 = 2B
B = 
B = 24 hrs for B alone
:
"If pipes A and B are used together, it takes 10 hours." we know B, therefore
 +  = 1
Multiply by 24A
24(10) + 10A = 24A
:
240 = 24A - 10A
240 = 14A
A = 
A = 17.143 hrs for A alone
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