Results 1 to 13 of 13
Thread: Basic Math Problem?

20130719, 00:22 #1
 Join Date
 Aug 2010
 Location
 Pa, USA
 Posts
 2,733
 Thanks
 126
 Thanked 686 Times in 623 Posts
Basic Math Problem?
An instrument store gives a 10% discount to all students off the original cost of an instrument. During a “Back to school” sale, an additional 15% is taken off the discounted price. Julie, a student at the local high school, purchases a flute for $306. How much did it originally cost?
Good luck,
Maud

20130719, 11:04 #2
 Join Date
 Feb 2001
 Location
 Willow Grove, Pennsylvania, USA
 Posts
 205
 Thanks
 4
 Thanked 49 Times in 40 Posts
$400
Do I have to show my work, teacher?

20130719, 11:48 #3
 Join Date
 Oct 2012
 Posts
 2,335
 Thanks
 13
 Thanked 267 Times in 260 Posts
Or if one figures in 5% sales tax, $381 give or take a few pennies, but there are also a couple potential trick elements in the mix, like if the instrument was not purchased there or what original cost might actually mean.
Last edited by F.U.N. downtown; 20130719 at 11:51.

20130719, 11:58 #4
Not figuring in any tax, the original price was $345.76.
Update  should be $353.76.Last edited by mrjimphelps; 20130719 at 12:10. Reason: recalculated

20130719, 12:01 #5

20130719, 12:11 #6
 Join Date
 Feb 2008
 Location
 A cultural area in SW England
 Posts
 3,452
 Thanks
 33
 Thanked 196 Times in 176 Posts
It's easy maths: $306 / 0.9 / 0.85 = $400. But surely it would, in reality, be priced at $399.99?!
BATcher
"The trouble with quotes on the internet is that you can never know if they are genuine."
Abraham Lincoln

20130719, 12:45 #7
 Join Date
 Oct 2012
 Posts
 2,335
 Thanks
 13
 Thanked 267 Times in 260 Posts

20130719, 13:41 #8

20130719, 14:22 #9
 Join Date
 Oct 2012
 Posts
 2,335
 Thanks
 13
 Thanked 267 Times in 260 Posts
Ya, and just divide by the sales tax amount prior to the two discounts for extra credit.
306/1.05/.85/.9=$380.95

20130720, 03:29 #10
 Join Date
 Feb 2008
 Location
 A cultural area in SW England
 Posts
 3,452
 Thanks
 33
 Thanked 196 Times in 176 Posts
In the UK, although we have an iniquitous rate  20% usually  of "Value Added Tax" (VAT), it is always included in the price for consumer purchases, so "the price you see is the price you pay" (haggling excepted).
For electronic goods and software, there seems to be a special "$1 translates to £1" conversion rate, which is why the UK is often referred to by nonnative computer and software manufacturers as "Treasure Island". I have no idea whether this conversion rate also applies to the cost of flutes...BATcher
"The trouble with quotes on the internet is that you can never know if they are genuine."
Abraham Lincoln

20130720, 13:07 #11
 Join Date
 Aug 2010
 Location
 Pa, USA
 Posts
 2,733
 Thanks
 126
 Thanked 686 Times in 623 Posts
This was an actual question given in a math class for education of immigrants to achieve a GED. The answer choices offered were:
A. $325.00
B. $375.00
C. $400.00
D. $408.00
E. $425.00
The most selected and also incorrect answer was $408.00 achieved by adding the 2 discounts (25%), calculating a discount of $102.00, then subtracting it from $408.00 which was a final price of $306.00.

20130720, 14:01 #12
 Join Date
 Jan 2001
 Location
 La Jolla, CA
 Posts
 1,495
 Thanks
 33
 Thanked 63 Times in 59 Posts
A 10% discount OFF the original price leaves 90% ON the original price.
If X is the original price, the first resulting price is 0.9X.
Then, if 15% is OFF this discounted price, that leaves 85% ON the price.
So, 0.85 x 0.9 x X = 306 (purchase).
Then, X = 306/0.765 = $400 as the original price.
Check it: $400 with a 10% discount = $360 ($40 off).
Then, 360 with a 15% discount = $54 off the $360.
So, 360  54 = $306.Last edited by kweaver; 20130720 at 14:19.

20130720, 17:08 #13
 Join Date
 Feb 2001
 Location
 Willow Grove, Pennsylvania, USA
 Posts
 205
 Thanks
 4
 Thanked 49 Times in 40 Posts
When I was in London some years ago, the same seemed to apply to books, especially paperbacks. Whatever number the US publisher printed on the book, that was the number of pounds charged. The currency exchange rate at the time was about 1.75 to 1, plus the fee at the exchange kiosk.