How many times will a 3 and a half inch circumference of a tire make full rotations every 10,000 miles. What would happen in the number of rotations if the circumference is both increased and or decreased by 20%?

Question

annalee607 · Answer

no

annalee607 · Answer

I need the equation and help.

jim_thompson5910 · Answer

first thing I would do is convert `10,000 miles` to inches

jim_thompson5910 · Answer

do you know how to do that @AnnaLee607 ?

annalee607 · Answer

63,360 inches is = 1 mile right?

jim_thompson5910 · Answer

yes

annalee607 · Answer

Would you multiple 10,000 by 63,360?

jim_thompson5910 · Answer

correct

annalee607 · Answer

633,600,000?

jim_thompson5910 · Answer

yep

jim_thompson5910 · Answer

633,600,000 inches = 10,000 miles

jim_thompson5910 · Answer

the tire has a `3 and a half inch circumference`

so how many full rotations will it do to cover 10,000 mi? 
equivalently, this is the same as asking
so how many full rotations will it do to cover 633,600,000 inches?

annalee607 · Answer

Would I divide 3.5 inches by 633,600,000

jim_thompson5910 · Answer

example: if I asked you "how many full rotations would the tire have to roll if the tire covers 7 inches?"

then you would do

7/3.5 = 2

so the tire has to roll a full 2 rotations to cover 7 inches

annalee607 · Answer

633,600,000/3.5=181,028,571.43

jim_thompson5910 · Answer

good, so it has to do 181,028,571.43 rotations if the tire is 3.5 inches in circumference

jim_thompson5910 · Answer

now increase the circumference by 20% and recompute the number of rotations

annalee607 · Answer

Would I multiply it by .20?

jim_thompson5910 · Answer

100% is the initial amount

increase by 20%

100% + 20% = 120% = 1.2

so you multiply by 1.2

jim_thompson5910 · Answer

if you decrease by 20%, then

100% - 20% = 80% = 0.80

so you'd multiply by 0.80

annalee607 · Answer

Increase 217,234,285.72 Decrease 144,822,857.14

jim_thompson5910 · Answer

let me check

annalee607 · Answer

Is that all?

jim_thompson5910 · Answer

no you should multiply 3.5 by 1.2

NOT the number 181,028,571.43

jim_thompson5910 · Answer

step 1) multiply 3.5 by 1.2

step 2) divide 633,600,000 over the result from step 1

annalee607 · Answer

Increase 150,857,142.86 Decrease 226,285,714.29

jim_thompson5910 · Answer

very good

jim_thompson5910 · Answer

if you increase the circumference by 20% then you go from
`181,028,571.43 rotations`
to 
`150,857,142.86 rotations`

jim_thompson5910 · Answer

if you decrease the circumference by 20% then you go from
`181,028,571.43 rotations`
to 
`226,285,714.29 rotations`

annalee607 · Answer

Thank you so much.

jim_thompson5910 · Answer

no problem