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me for my assignment and please show solutions


1.) Mr. Aquino mixed 40 kg of cashew nuts with 100 kg of peanuts costing $ 100/kg. The assorted product now sells for $ 130/kg at a profit of 25% of the cost. How much did the cashew nuts originally cost per kilogram?

2.) Alcohol solutions of 90% and 58% concentration are mixed together to make a 20 litre 78% solution. How much of each needed?

3.) How many litres of water must be added to 60 mL of the very corrosive glacial acetic acid (pure or 100% acetic acid) to make 6% acetic acid?

2006-12-30 19:09:17 · 7 answers · asked by Anonymous in Science & Mathematics Mathematics

just don't answer if you don't know

2006-12-30 19:19:12 · update #1

7 answers

1.40x+100(100)=(140)*130*100/125
40x+10000=14560
40x=4560
x=4560/40
=114
the price of cashew is rs.114/kg

2.x+y=20
0.9x+0.58y=20*0.78
multiplying by 100
90x+58y=1560
58x+58y=1160
42x=400
x=400/42=9.5 approx.
so 9.5 litre of 90% and 10.5 litre of 58% solution

3.60=(60+x)*0.06
multiplying by 100
6000+=360+6x
6x=5640
x=940
so 940 litres of water must be added

2006-12-30 19:21:15 · answer #1 · answered by raj 7 · 1 1

1. let cashew nuts = c;
$ peanuts = 100*100 = 10000
$ mixture = 130*140 = 18200 (where 40+100 is the total mass)
this implies that (10000+c)*1.25=18200
so c = (18200/1.25)-10000
so c = $4560
hence cost per kg of casheews is 4560/40 = $114/kg

2. let the amount of solution 90% = x, the amount of the other solution used (58%) is therefore 20 - x, where x is in litres.

Now you have;

[(90 * x)+(58*(20-x))]/20 = 78

which solves to (20*78) - (58*20) = 32*x
that is 400 = 32*x
so x = 12.5 litres

so 12.5 litres of 90% alc. and 7.5 litres of 58% alc.

3. you can do this question if you assume it is by % by volume
If you're trying to do questions like this by yourself try to simplify the problem, think of the case where you have 1 litre of the solution if you add 1 litre of water you have a 50% solution, 2 litres and you have a 33.33% solution, 3 litres = 25% solution. Whilst you could keep doing this it is not what your teacher wants you to do: notice that the %concentration = Volume acid / total volume
so for 6% = 60 / 1000
so the volume of water added is 1000-60 = 940 mL so 0.94 L

2006-12-30 19:32:48 · answer #2 · answered by sribabble 1 · 2 0

The object of doing an assignment is to cement your learning. If you 'cheat' you learn nothing. So what I will give you is a way to answer the problems the correct way

1) start with what you know. You know how much the mixed nuts sell for and how much profit you are making. Use this to determine how much your cost is for the mixed product, then you can figure out how much the cashews cost.

2) in any problem like this you are not obliged to use the quantity they provide until the very end. It's much easier to determine what the solutions would contain for quantities such as 1L, 100L, ect. Once you have the answer for this you need only convert to the quantity they want.

3) What does % mean? If you know that then the answer comes around really quick.

2006-12-30 19:31:14 · answer #3 · answered by beenthere 2 · 1 1

[1]
total revenue = (40+100) * 130 = 18200
total cost = 18200*0.80 = 14560
peanuts cost = 100*100 = 10000
cashews cost per kg = (14560-10000)/40 = 114

[2]
90x + 58y = 78*20
90x + 58y = 1560
58y = 1560 - 90x
y = (1560-90x)/58

[3]
ratio acid/water=6/94 = 60mL/x
94*60mL = 6x
water = x = 940mL

2006-12-30 19:38:22 · answer #4 · answered by Johnny Handsome 2 · 1 0

question 1:

let the cost of caschews per kg be x
Now,
cost of mixture= 40x + 100*100
cost per kg= (40x + 100*100)/140
if we need 25 percent profit we multiply it with 1.25
So,
[(40x + 100*100)/140]*1.25=130

Solve for x, x=114,
SO cost of caschews is $114/kg

question2:
Say, x liters of 90% alc is needed
then 20-x of 58% is needed
Quantity of alcohol in mixture= 0.9x +0.58(20-x)
Concentration = Alcohol / total volume=0.78(final concentration)
Hence,
[0.9x +0.58(20-x)]/20=0.78
Solve for x,
x=12.5
So, you need 12.5 lit 90% and 7.5 58% solutons

question3:
Say we need x ml water
Now,
we have total volume = 60+x ml
Volume of acid= 60 ml
concentration=
60/(60+x)= 0.06 ....(because final needed is 6%)
solve for x,
x=940
therefore, water needed is 940 ml or0.94 litres

2006-12-30 19:27:56 · answer #5 · answered by gp2much 2 · 1 0

use algebra to solve.let each of the variable you need to find be x.form an equation linking all the info and solve for x.

2006-12-30 19:55:57 · answer #6 · answered by Save_Us.925 2 · 0 2

not now

2006-12-30 19:12:41 · answer #7 · answered by agarwalsankalp 2 · 0 2

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