## Claire4christ 3 years ago And i need help with these problem. An alloy of tin is 15% tin and weighs 20 pounds. A second alloy is 10% tin. How much (to the nearest tenth lb.) of the second alloy must be added to the first alloy to get a 12% mixture. ______ pounds

1. Claire4christ

Problem 1: A jeweler is using an alloy, a mixture of metals. He has 10 pounds of the alloy. 2% is the rare metal robium. He has another source which is 5% robium. He wishes to combine these mixtures to form a mixture that is 3% robium. Solution: 1. Identify the variables. (0.02)(10) The quantity of robium in material 1 (5%)(x) The quantity of robium in material 2 (0.03)(x+10) The quantity of the desired mixture 2. Write an equation. 5% x + (0.02)(10) = (0.03)(x+10) The equation required. 3. Perform the Solution. 0.05x + 0.2 = .03x + 0.3 = 0.02x = 0.1 4. Write the answer. x = 5 The desired amount.

2. andriod09

just do what i did. use the percent bar, then the butterfly method. want me to start for you? here: |dw:1349374188909:dw|

3. Claire4christ

sorry its not clear to me i can't see the top number

4. andriod09

at the very top, it isn't a number, its the % symbol. all you do is fill it in, the top number, is the number your trying to find, x, the bottom number, not the 100, is the total, then you put what percent you are trying to find below the percent sign and above the 100.

5. Claire4christ

so its (0.15)(20) (10%)(x) (0.12)(x+10)

6. Chlorophyll

15 * 20 + 10x = 12 ( 20 + x) @Claire4christ Can you continue?

7. Claire4christ

did you see example above???

8. Chlorophyll

9. Claire4christ

that's one of the examples

10. Claire4christ

do you see where it says problem 1 that;s the example

11. Claire4christ

can u explain me than plz

12. Chlorophyll

I just show you the result equation, then you solve it yourself!

13. Chlorophyll

Multiply the percentage with its mass :)

14. Chlorophyll

Is it clear to you now?

15. Claire4christ

300+10x=240=2x

16. Claire4christ

300+240???

17. Claire4christ

60

18. Chlorophyll

15 * 20 + 10x = 12 ( 20 + x) 300 + 10x = 240 + 12x

19. Claire4christ

60+10x=2x

20. Chlorophyll

Do you understand my calculation above?

21. Claire4christ

yes

22. Chlorophyll

Where do you get 60+10x=2x?

23. Claire4christ

300-240???

24. Chlorophyll

15 * 20 + 10x = 12 ( 20 + x) 300 + 10x = 240 + 12x -> 2x = 60 You should make each line worth your while, instead of jumping all over !!!

25. Chlorophyll

Now I hope you're fine with x = ...?

26. Claire4christ

30

27. Claire4christ

how did you get 15

28. Chlorophyll

15%

29. Chlorophyll

I just make your life easier by multiplying all with 100 :)