Maths help please (1 Viewer)

[devils_daughta8]

okay can someone please help with this question?

Sandra buys a used car with a cash price of $12000 on the following terms: 20 % deposit with the balance paid aat $89.23 per week for 3 years. Calculate:
a) the deposit : 12000* 20% = $ 2400
b) the balance owing: 12000 - 2400 = $9600
c) the total cost of the car: ??? please help
d) the flat rate of interest charged: ??? please help with this too


im really confused lol
thankyou in advanced

P.S: does anyone know how to put in a set of scores into a calculator in statistics function??

 

[cro_angel]

Total cost of the car is the deposit + total weekly repayments
therefore total cost is 2400 + (89.23 x 52 x 3)
TC= $16319.88
Flat rate of interest would be amount paid divided by the original amount which it would be if you paid in cash...
so 12000/16319.88 x 100 (to get to a %) = 73.53%
Divide this by 3 because it is paid over 3 years..
73.53/3 = 24.51%
Im not sure about the second part because it seems a bit high.. ive never really had to find that out

I use a sharp scientific calculator (EL-531RH) and to put a set of scores you press [2ndF] [DRG] [1] to get it into statistics
Say you were entering the scores 1, 2 and 3 you would press
[1] [M+] [2] [M+] [3] [M+]
Then at the end it says the number 3 there which means the total number of scores that have been entered..
to find the mean you press [RCL] [4] and to find the standard deviation you press either [5] or [6] depending on whether its a sample or the population

 

[devils_daughta8]

thankyou so much, u are a great help

 

[PC]

Hi there! Just wanted to put you straight on that last part.

(a) Deposit = 20% of $12000 = 0.20 x 12000 = $2400 √

(b) Balance owing after deposit is paid = Cash price – Deposit = 12000 – 2400 = $9600 √

This answer is quite important to get your head around. At this stage, we're still at the first day of the 3 year thing. So far, we're still in the car yard. We've paid the deposit, so the amount that still owes when we drive away with the car is $9600. Because we've paid SOME of the total amount, we don't get charged interest on the WHOLE price of the car. Interest is charged on the amount that we still owe – $9600. Makes sense? Why get charged interest on what you've already paid.

(c) Total cost of car = Deposit + Payments = 2400 + (3 x 52 x 89.23) = $16319.88 √

Now comes the last bit. The question asks for the FLAT (or SIMPLE) interest rate, so use the flat rate formula, I = Prn (or whatever form you use).

First of all, we know the interest that has been paid. Since Sandra paid $16319.88 for the car, but it was originally priced at $12000, she must have paid the extra in interest.

Then use the formula to find "r". But remember that the Principal is $9600, and not $12000.

(d) Interest paid = 16319.88 – 12000 = $4319.88

Therefore I = Prn
4319.88 = 9600 x r x 3
4319.88 = 28800r
r = 4319.88 ÷ 28800 = 0.1499958333 = 14.9958333% = 15%

Hope that helps.

On that last bit ... do you have access to a graphic calculator?

 

[cro_angel]

yeh that prob makes more sense (the interest rate).. i think i remember now getting a similar question wrong in one of my exams or the trials.. blah that whole topic has always been my weakness (thank goodness they give some marks for working out lol dont know where id be without it).
hmm i finished my gen maths hsc exam with 15 mins to spare without a graphics calculator.. damn i wonder how quickly those who have them must finish!

 

[PC]

From what I can gather from reading various messages on this forum is that most people think that graphic calculators are more trouble than they are worth - and based on the 2004 HSC I tend to agree, but I'll tell you something for free ... I won't use anything else for statistics! Just type in the numbers and voila! All the results you'll ever need are there!

 

[sNiPeR_24]

Graphics calculators make life so much easier if you can use them properly.

 

[Trev]

do you get to use graphic calculators? use a program on the computer - "Graphmatica".

 

[PC]

You can use Graphics Calcs at any time anywhere - including in the exam.

You can't use a computer programme in your exam unfortunately.

Is "Graphmatica" some sort of sub-application of "Mathematica"?