gas prices went down 10% last year and then rose 20% this year. over the two years, gas went up what percent?
2006-10-25 16:12:44 · 9 answers · asked by woodaka2004 1 in Science & Mathematics ➔ Mathematics
It's a trick question.
Pretend gas starts out at $1.00 a gallon. If it fell 10% you'd end up with $.90 a gallon and if that went up 20% you'd get $1.08 a gallon. That's an 8% increase.
Use this equation:
Final Price = 1.2 ( .9 * Starting Price)
Simplify to
Final Price = 1.08 * Starting Price
As you can see, gas would go up 8% when you're all said and done.
2006-10-25 16:26:39 · answer #1 · answered by Roman Soldier 5 · 1⤊ 1⤋
% of growth = [1 - (%of loss in first year/100)][1 + (%of growth in the second year/100)
% of growth = [1-(10/100)][1+(20/100)]
= (90/100)(120/100)
= (9/10)(12/10)
= (108/100)
= 1.08%
The gas prices have gone up by 1.08%
2006-10-26 01:18:10 · answer #2 · answered by Akilesh - Internet Undertaker 7 · 0⤊ 1⤋
10%
2006-10-25 16:20:19 · answer #3 · answered by Anonymous · 1⤊ 1⤋
take it to be 100 units (initially)...
then, yr 1: cost=100- (100*10/100)
=90
yr 2 : cost= 90+ (90*20)/100
=108
thrfore total rise= {(108-100)*100}/100
=8%
2006-10-25 17:11:56 · answer #4 · answered by pat 1 · 2⤊ 0⤋
i think of oil costs will proceed to upward thrust in the long term. call for for oil has continually greater desirable, and with the present enlargement of China and India this would not seem to alter any time quickly. the supply of oil has peaked or will height interior of right here couple of years, no one can assume while yet maximum individuals agree it is going to ensue quickly. as an occasion the CEO of GM predicted that oil production peaked final year. As call for is becoming and grant is sturdy or going to start lowering costs will proceed to enhance. you are able to continually desire that yet another variety of capability takes over from oil, yet i do no longer think of that it will ensue any time quickly.
2016-10-16 10:17:33 · answer #5 · answered by saleh 4 · 0⤊ 0⤋
take it to be 100 units (initially)...
then, yr 1: cost=100- (100*10/100)
=90
yr 2 : cost= 90+ (90*20)/100
=108
therefore total rise= {(108-100)*100}/100
=8%
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2006-10-27 22:36:01 · answer #6 · answered by slimy dude 2 · 0⤊ 0⤋
ignore the % part, it is apparently freaking you out.
this is a simple subtraction problem:
20-10=10
2006-10-25 16:22:33 · answer #7 · answered by Anonymous · 0⤊ 1⤋
!100-10/100)(100+20/100)
=0.9*1.2=1.08
they have increased by 8%
2006-10-25 16:22:38 · answer #8 · answered by raj 7 · 1⤊ 1⤋
(1 - .1)x = .9x
(1 + .2)(.9x) = 1.2 * .9x = 1.08x
(1 + .08)x = x + .08x
Therefore thats a 8% increase
2006-10-25 16:30:06 · answer #9 · answered by Sherman81 6 · 1⤊ 1⤋