Needing help with a math problem...

  1. I have a test tomorrow & I'm stumped on this question out of the study guide.

    What is $6800 at 4% compounded monthly for 9 months?

    I have
    6800(1+.04/12)12x.75exponent
    6800(this is where I have trouble since the 3 is repeating)(1.003)9exponent
    =$6985.82

    The study guide says the correct answer is $7006.74. I think I messed up with the .04/12 since you get a repeating 3. What do you do with it?
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  2. 17 Comments

  3. by   truern
    Omg!! Drug calcs I can do, but THIS??

    Sorry

    Just a thought, though...have you tried to find a bank calculator online?
  4. by   jaysma
    I used Excel and got the correct answer, but I can't figure how to work it out.

    This is the formula, if it helps any-

    A=P(1+R/N)NxT (exponents)

    A= Accumulated amount of $
    P= Principle (what you started with)
    R= Rate in decimal form (example 6% = 0.06)
    N= # of times compounded per year
    T= time in years

    .04/12 is the yearly interest. It's .00333333333 neverending. When I add 1 to it (1+r/n) I of course still get a repeating number. So I called it 1.003 (which is wrong) to the 9th power multiplied by 6800.

    BTW, this is Fundamentals of Math! I dread going into algebra the 2nd 1/2 of the semester if it's anything like this!
  5. by   DutchgirlRN
    My 80 year old Dad could work this in 2 seconds flat. It's 2100 here and I'm sure he's already asleep. If you still need the answer in the AM I could get the answer from him.
  6. by   jaysma
    Quote from DutchgirlRN
    My 80 year old Dad could work this in 2 seconds flat. It's 2100 here and I'm sure he's already asleep. If you still need the answer in the AM I could get the answer from him.
    Oh, no biggie. My test is in the am. I understand everything else so if I miss this I won't fail
  7. by   DutchgirlRN
    Cool ! I'm testing myself tomorrow. ACLS renewal time, oh boy fun stuff !
  8. by   Fugitive
    Quote from jaysma
    I used Excel and got the correct answer, but I can't figure how to work it out.

    This is the formula, if it helps any-

    A=P(1+R/N)NxT (exponents)

    A= Accumulated amount of $
    P= Principle (what you started with)
    R= Rate in decimal form (example 6% = 0.06)
    N= # of times compounded per year
    T= time in years

    .04/12 is the yearly interest. It's .00333333333 neverending. When I add 1 to it (1+r/n) I of course still get a repeating number. So I called it 1.003 (which is wrong) to the 9th power multiplied by 6800.
    I'm almost positive that you should have set up the equation like this:

    6800(1+.04/9)^9x.75

    If N= # of times compounded per year, then the 4% is compounded 9 times.

    The important part of the question is asking for "4% compounded monthly for 9 months."

    Again the key is MONTHLY for 9 months. So if you only get 9 months and it is compounded monthly, it can only be compounded 9 times.

    N=9

    But at I said earlier, almost positive... Haha!

    Quote from jaysma
    What is $6800 at 4% compounded monthly for 9 months?

    I have
    6800(1+.04/12)12x.75exponent
    6800(this is where I have trouble since the 3 is repeating)(1.003)9exponent
    =$6985.82

    The study guide says the correct answer is $7006.74. I think I messed up with the .04/12 since you get a repeating 3. What do you do with it?
  9. by   jaysma
    Quote from Fugitive
    I'm almost positive that you should have set up the equation like this:

    6800(1+.04/9)^9x.75

    If N= # of times compounded per year, then the 4% is compounded 9 times.

    The important part of the question is asking for "4% compounded monthly for 9 months."

    Again the key is MONTHLY for 9 months. So if you only get 9 months and it is compounded monthly, it can only be compounded 9 times.

    N=9

    But at I said earlier, almost positive... Haha!
    That makes sense! What would the exponent then be? 9 x .75 = 5.25. Doesn't it have to be a whole number?
  10. by   Fun2, RN, BSN
    Quote from DutchgirlRN
    My 80 year old Dad could work this in 2 seconds flat. It's 2100 here and I'm sure he's already asleep. If you still need the answer in the AM I could get the answer from him.
    Must be nice to have not grown up with a calculator when you were learning math. lol

    Sometimes technology is not good. (Where's my brain? It's in its calculator case on top of my chemistry book!)

    Good luck to those taking tests!
  11. by   Fugitive
    Quote from jaysma
    That makes sense! What would the exponent then be? 9 x .75 = 5.25. Doesn't it have to be a whole number?
    Actually 9*.75 = 6.75
    It's asking for 75% of 9.

    25% of 9 is 2.25
    2.25 + 2.25 + 2.25 = 6.75 + 2.25 = 9

    No, I don't think it has to be a whole number. I tried rounding to 7 and also to 6.8, but the answer became too large. 7014 and 7008 respectively. Leaving the exponent at 6.75 gives the answer of 7006.

    Again I have to say that I am not 100% sure that I am right. I haven't taken a math class in over 5 years. I've never much cared for these accounting/banking problems.

    Best of luck on your exam!
  12. by   Race Mom
    Here's my go at it...and I got the right answer if that helps.

    A (amount)
    A=6800(1+.04/12) 9 (exponent)
    A=6800(1.00333333) 9 (exponent) my calc only went to five 3's but got the right answer
    A=6800 X 1.034025
    A= 7006.74 (rounded up)

    I dont have exponent on my basic calc, but 1st time I entered it was to the 1st power, than hit the X key, then hit the = key 8 more times to come up with the 1.034025.

    Good luck and hope you get to use a calc!!!!!!!!!!
    Lisa
  13. by   jaysma
    Quote from Woogy
    Here's my go at it...and I got the right answer if that helps.

    A (amount)
    A=6800(1+.04/12) 9 (exponent)
    A=6800(1.00333333) 9 (exponent) my calc only went to five 3's but got the right answer
    A=6800 X 1.034025
    A= 7006.74 (rounded up)

    I dont have exponent on my basic calc, but 1st time I entered it was to the 1st power, than hit the X key, then hit the = key 8 more times to come up with the 1.034025.

    Good luck and hope you get to use a calc!!!!!!!!!!
    Lisa
    That's what my instructor said this morning when I asked about it. We're allowed to use calculators, but not scientific ones, which I guess is good since no calculators at all can be used on the NLN test. Let's just hope this kind of problem (repeating #'s) isn't on it

    There were 60 of these problems on the test. I'll get my results this afternoon. Thanks for the help everyone!
  14. by   Race Mom
    I took NLN 5 years ago and there weren't any questions like that. Maybe exponents, but not compounding interest.
    Lisa

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