waheguru 2 years ago Can someone please help me with this problem, I do not understand how to solve

1. waheguru

2. waheguru

How do i solve this?

3. Azteck

Let the part of it that's being invested at a rate of 5% per annum be x. Let he other part that's being invested at 7.2% "5000-x".

4. waheguru

can it not also be y ?

5. Azteck

Why would you want two variables when you can solve it using one? Do you want to make your life harder?

6. waheguru

Its because i am learning graphing at the moment so i thought there would be y in there

7. Azteck

Does the question have the word sketch/draw or graphically in it?

8. waheguru

no

9. Azteck

Then what kind of reason was that?... Now let's continue on with the question rather than giving random excuses as to what you're learning.

10. waheguru

sorry

11. Azteck

Write 5% as a decimal.

12. Azteck

Also write 7.2% as a decimal.

13. waheguru

0.05

14. waheguru

0.072

15. Azteck

Sorry I meant fraction. My apologies.

16. waheguru

50/1000 75/1000

17. Azteck

Make it into the simplest form please. If you don't know how to simplify fractions into its simplest form, then I suggest you use your calculator.

18. waheguru

1/20 and 3/40

19. Azteck

75?

20. Azteck

The question says 7.2%....not 7.5%....

21. waheguru

9/125

22. Azteck

You only got one correct. Please rewrite 7.2% as a fraction again please.

23. Azteck

Yep you're correct.

24. Azteck

Sorry about that, my comp lagged out.

25. Azteck

Okay now. Do you agree that (x times 5%)+[(5000-x) times 7.2%)]=349?

26. waheguru

yes

27. Azteck

Okay, now change the 5% and 7.2% into the fractions you wrote previously and show me your equation.

28. waheguru

1/20 x + 9/25 (5000-x) = 349

29. Azteck

Yep great! Excellent.

30. Azteck

Now. You just figured the equation that would lead you to finding x. $\frac{ x }{ 20 }+\frac{ 9(5000-x) }{ 125 }=349$

31. waheguru

oh... yea

32. Azteck

It's 125.

33. Azteck

I'm just letting you go for just writing 25 but I will let you go this time due to the probability of that being a typo.

34. waheguru

yea

35. Azteck

Okay, so when you get rid of the fractions by multiplying both sides with the Lowest common multiple, tell me what you get.

36. waheguru

500 LCD

37. Azteck

yep.

38. Azteck

Multiply by 500 to both sides.

39. Azteck

Tell me what you get. Afterwards, you would have to expand/distribute the brackets/paranthesis.

40. waheguru

Ill do that, but just for knowledge this can also be answered by using the decimals (0.05 and 0.075) right

41. waheguru

i ment 0.072

42. Azteck

Yea of course.

43. Azteck

I just reckon fractions are clearer and you would understand a bit better.

44. Azteck

So what did you get?

45. waheguru

I find fractions a bit difficult so i did decimals, 0.05x + 0.072(5000-x) = 349

46. waheguru

0.05x + 360-0.072x = 349

47. Azteck

Okay...Well then expand/distribute the brackets/paranthesis...

48. waheguru

and 0.05x - 0.072 = -11

49. Azteck

Where's the x gone mate?

50. waheguru

sry (you are am amazing teacher you can catch the slighest mistakes =) 0.05x - 0.072x = -11

51. Azteck

Okay collect likes terms. That means group the x's together.

52. Azteck

like terms*

53. waheguru

-0.022x = -11

54. waheguru

x= -11/-0.022

55. waheguru

x = 500

56. waheguru

wow

57. Azteck

Yep and then what do you get for the other one.

58. Azteck

?*

59. Azteck

There's two parts.

60. Azteck

That's the first part where it was invested at a rate of 5% p.a

61. Azteck

So what about the part where it was invested at a rate of 7.2%?

62. waheguru

4500 the rest of the money

63. Azteck

Correct. Awesome.

64. waheguru

wow, you are just an amazing teacher. thank you soo much

65. Azteck

I will show what I did using fractions. This just give you a look at a different perspective in solving these. $25x+36(5000-x)=174500$ $25x+180000-36x=174500$ $11x=180000-174500$ $11x=5500$ $x=500$

66. Azteck

And no worries. Good work.

67. waheguru

Mr, Aztech are you usually available at this time so I can ask you for help

68. Azteck

Not all the time. I'm also busy with my own work. So some days I will be off doing my work and other days I will be resting and so on. This is only just a bit of fun to help others with their homework.

69. waheguru

Thankyou sir