[Tutor] Tutor Digest, Vol 142, Issue 10

[Ken Hammer]

I have a more simple-minded solution.  The error appears to occur in testing without revealing the problem by use of $1 base price in the test.  Using $10,000 as the base price in the test reveals absurd numbers.  I think the real problem lies in the inclusion of base price inappropriately, twice as in:

>dealerPrep = basePrice + 500
>destinationCharge = basePrice + 250

"basePrice" has no place in those two lines.  500 and 250 alone express the definition of the challenge.

Ken



In <mailman.13.1449939602.12987.tutor at python.org>, on 12/12/15 
   at 12:00 PM, tutor-request at python.org said:



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>Today's Topics:

>   1. Calculation error with a simple program (Jim Gallaher)
>   2. Re: Calculation error with a simple program (Alan Gauld)
>   3. Re: Calculation error with a simple program (Laura Creighton)


>----------------------------------------------------------------------

>Message: 1
>Date: Sat, 12 Dec 2015 01:03:05 -0600
>From: Jim Gallaher <jcgallaher78 at gmail.com>
>To: tutor at python.org
>Subject: [Tutor] Calculation error with a simple program
>Message-ID: <566BC6A9.6090206 at gmail.com>
>Content-Type: text/plain; charset=utf-8; format=flowed

>Hi everyone. I'm reading through a beginners Python book and came up  with
>a super simple program. I'm not getting any errors and everything  runs
>through, but there's a logical calculation error. What the program  does is
>take an amount and calculate a couple percentages and add a  couple fees.

>For example, if I put in a value of 1, it will output 752.12 as the sub 
>total and 753.12 as the grand total. It's off by 1 on sub total and 2 on 
>grand total.

>Thanks in advance! Jim Gallaher

># Car Salesman Calculator

># User enters the base price of the car and the program adds tax,  license,
>dealer prep, and destination charge.

>print("Car Sales Calculator")
>basePrice = int(input("Please enter in the price of the car: "))

># Misc charges to be added to the total cost of the car
>tax = basePrice * .07
>license = basePrice * .05
>dealerPrep = basePrice + 500
>destinationCharge = basePrice + 250

># Add the total misc charges together
>subTotal = float(tax + license + dealerPrep + destinationCharge)

># Add all the misic charges and include the base price
>grandTotal = float(subTotal + basePrice)

># Display the results
>print("\nThe sub total is", subTotal)
>print("\nYour grand Total is", grandTotal)

>input("\nPress the enter key to close the program.")


>------------------------------

>Message: 2
>Date: Sat, 12 Dec 2015 08:04:52 +0000
>From: Alan Gauld <alan.gauld at btinternet.com>
>To: tutor at python.org
>Subject: Re: [Tutor] Calculation error with a simple program
>Message-ID: <n4gkf4$e99$1 at ger.gmane.org>
>Content-Type: text/plain; charset=utf-8

>On 12/12/15 07:03, Jim Gallaher wrote:

>> For example, if I put in a value of 1, it will output 752.12 as the sub 
>> total and 753.12 as the grand total. It's off by 1 on sub total and 2 on 
>> grand total.

>Are you sure? Lets check the values...

>> basePrice = int(input("Please enter in the price of the car: "))

>=> 1

>> tax = basePrice * .07

>=> 0.07

>> license = basePrice * .05

>=> 0.05
>> dealerPrep = basePrice + 500

>=> 501

>> destinationCharge = basePrice + 250

>=> 251

>> # Add the total misc charges together
>> subTotal = float(tax + license + dealerPrep + destinationCharge)

>=> 0.07 + 0.05 + 501 + 251 => 752.12

>> # Add all the misic charges and include the base price
>> grandTotal = float(subTotal + basePrice)

>=> 752.12 + 1 => 753.12

>Looks like Python got it right to me?




-- 
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K.F.Hammer Associates                                         Ken Hammer
management consultations                      Saint Johnsbury, VT  05819
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