SOLUTION: plEase help!urgent!
1. An alloy contains 20% gold and another contains 40% gold. How much of each must be mixed to produce 200kg of 25%gold?
2. A dairy man wishes to prepar
Algebra.Com
Question 205016: plEase help!urgent!
1. An alloy contains 20% gold and another contains 40% gold. How much of each must be mixed to produce 200kg of 25%gold?
2. A dairy man wishes to prepare cream containing 5% butterfat. How much cream of 25% butterfat must be added to 50 kg of cream approximately containing 4% butterfat?
3. Mart is twice as old as Nald. In six years, he will be four times as old as Nald was three years ago. What are their present ages?
4. A freight train traveling at a rate of 60kph leaves a city. Three hours later, an express train whose average rate is 80kph leaves the same city traveling in the same direction. How long will it take the express train to overtake the freight train?
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
1. An alloy contains 20% gold and another contains 40% gold. How much of each must be mixed to produce 200kg of 25%gold?
200 kg @ 25% = 50 kg of gold
x = amount of 20% alloy
x*0.2 + (200-x)*0.4 = 50
2x + 4(200-x) = 500
2x + 800 - 4x = 500
-2x = -300
x = 150 kg of 20% alloy
50 kg of 40% alloy
----------------------
2. A dairy man wishes to prepare cream containing 5% butterfat. How much cream of 25% butterfat must be added to 50 kg of cream approximately containing 4% butterfat?
50*0.04 + x*0.25 = (50+x)*0.05
50*4 + 25x = (50+x)*5
Solve for x.
------------------
3. Mart is twice as old as Nald. In six years, he will be four times as old as Nald was three years ago. What are their present ages?
m = 2n
m+6 = 4(n-3)
2n+6 = 4n-12
-2n = -18
Nald is 9
Mart is 18
------------
4. A freight train traveling at a rate of 60kph leaves a city. Three hours later, an express train whose average rate is 80kph leaves the same city traveling in the same direction. How long will it take the express train to overtake the freight train?
---
In 3 hours the freight train goes 180 km.
The fast train gains on it at 80-60, or 20 kph
180/20 = 9 hours to overtake it.
RELATED QUESTIONS
One alloy contains 80 % gold (by weight) and another alloy contains 55 % gold. How many... (answered by josgarithmetic)
AN alloy containing 40% gold and an alloy containing 70% gold are to be mixed to produce... (answered by Maths68)
one alloy contains 80% gold (in weight) and another alloy contains 55% gold. how many... (answered by mananth)
How many grams of pure gold must be mixed with 40% gold alloy to produce 100 grams of 52% (answered by josmiceli)
A goldsmith has two gold alloys. The first alloy is 20% gold; the second alloy is 60%... (answered by anteater)
One alloy contains 80% gold and another alloy contains 55% gold. The two alloys are... (answered by mananth,dkppathak)
A goldsmith has two gold alloys. The first alloy is 20% gold and the second alloy is... (answered by ikleyn)
An alloy that is 50% gold is to be combined with an alloy that is 75% gold to produce 20... (answered by mananth)
One alloy contains 80% gold (by weight)and another alloy contains 55% gold.how many grams (answered by Alan3354)