GMAT Prep #2_PS Percents #35

[kwah]

Please advise how to achieve the result in the attached question. Thanks, K

Answer: E

[klmehta03]

Let the purchase price be X
at 8% sales tax (ST) ; ST @ 8%= 0.08X... (1)
at 5% sales tax (ST) ; ST @ 5%= 0.05X... (2)
0.08X-0.05X=12
X=400
Total proce w/ ST= 400+400*(0.08)
=432

[Bill@VeritasPrep]

I solved this one a little differently. We have a difference of 3% in sales tax rates and $12 in purchase price. At 3%, we are paying $3 in tax per $100. 12/3 = 4, so the base price is $400. At 8%, we're paying $8 per $100, so the tax amount is 8*4 = 32.

400 + 32 = $432

[GMATGuruNY]

I posted an alternate approach here:

https://www.beatthegmat.com/percent-change-t107610.html

[Anurag@Gurome]

Please advise how to achieve the result in the attached question. Thanks, K

Answer: E

Let us assume that Connie's purchase = $x
Then 5% of x = 8% of x - 12
0.05x = 0.08x - 12
12 = 0.03x
So, x = $400

Therefore, the total amount Connie paid for her purchase including sales tax = 400 + (0.08 * 400) = [spoiler]$432[/spoiler]

The correct answer is E.