I need an algebra gas equation !?

Question

I need a formula that says:

For every 10mph over 55 mph, (miles per hour) your mpg (miles per gallon) decreases by 10%

Lets say you got 19 mpg at 55 mph, what would you get at 75 mph? I am having a very hard time trying to figure this one out.

Thanks in advance!

Answer 1

Let S = your speed (which u gave as 75)
M = your mileage mpg (which you gave as 19)


To compute your new mileage....

New M = 19 - [(S - 55)/10] 0.1(19)

Answer 2

Miles per gallon at 75 mph.

75 - 55 = 20

So miles per gallon at 65 are 10% less than at 55. And miles per gallon at 75 are 10% less than at 65.

(1 - 0.1)² = 0.9² = 0.81

mpg at 75 mph = 0.9² * 19 = 0.81 * 19 = 15.39 mpg

Answer 3

Let the speed = s and let mpg =m
Then m(final) = m(start) - 10/100[m(start)](s-55)/10

So m(final) = m(start) -[m(start)](s-55)/100

Substitute the specific values. Then you get
m(final) = 19 -(19)(75-55)/100 =19 -19(20/100)
= 19(1-0.2) = 19(0.8) =15.2

Answer 4

what you have is an areithmetic progression

for every increase of 10 you get a decrease of 10%
hence:

55........65........75........ common diff is 10
19........17.1.....15.2..... common diff is 1.90

so our formula is:

mpg = 19 - 1.90(X - 55)/10

X is the kph for every 10 progression (e.g. 65 or 75 or 85 etc.)

just substitute the value to this variable & you'll get a correct answer everytime

mabuhay !!

Answer 5

19-(1.9)^2=15.39