## waheguru 3 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. anonymous

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. anonymous

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. anonymous

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

8. waheguru

no

9. anonymous

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. anonymous

Write 5% as a decimal.

12. anonymous

Also write 7.2% as a decimal.

13. waheguru

0.05

14. waheguru

0.072

15. anonymous

Sorry I meant fraction. My apologies.

16. waheguru

50/1000 75/1000

17. anonymous

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. anonymous

75?

20. anonymous

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

21. waheguru

9/125

22. anonymous

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

23. anonymous

Yep you're correct.

24. anonymous

Sorry about that, my comp lagged out.

25. anonymous

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

26. waheguru

yes

27. anonymous

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. anonymous

Yep great! Excellent.

30. anonymous

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. anonymous

It's 125.

33. anonymous

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. anonymous

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. anonymous

yep.

38. anonymous

Multiply by 500 to both sides.

39. anonymous

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. anonymous

Yea of course.

43. anonymous

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

44. anonymous

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. anonymous

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

48. waheguru

and 0.05x - 0.072 = -11

49. anonymous

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. anonymous

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

52. anonymous

like terms*

53. waheguru

-0.022x = -11

54. waheguru

x= -11/-0.022

55. waheguru

x = 500

56. waheguru

wow

57. anonymous

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

58. anonymous

?*

59. anonymous

There's two parts.

60. anonymous

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

61. anonymous

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

62. waheguru

4500 the rest of the money

63. anonymous

Correct. Awesome.

64. waheguru

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

65. anonymous

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. anonymous

And no worries. Good work.

67. waheguru

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

68. anonymous

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