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A rubber ball dropped 80 feet rebounds on each bounce 3/5 of the height from which it fell. How far will it ravel before coming to rest?

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for all you smart fellers

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320 feet?

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It's a rubber ball, it won't ravel atall.


unless ravel means something different where you come from. 😛

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Originally posted by Drew L
A rubber ball dropped 80 feet rebounds on each bounce 3/5 of the height from which it fell. How far will it ravel before coming to rest?

😀

for all you smart fellers
It wont "travel" as it was dropped from height, if it was dropped perfectly vertical, it will rest where it first bounced. (in theory!)

😉

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Originally posted by smomofo
320 feet?
Horah!

320 feet it is.

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Cool. I actually figured that out on my own! Thanks.

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Originally posted by smomofo
Cool. I actually figured that out on my own! Thanks.
yeah, it was on my pre-calculus final.

A1 / 1 - r where A1 = initial drop and r = rate of rebound

First find the height of the first rebound

80 * (3/5) = 48

Second Use the geometric infinite geometric convergent formula [ once for the drop and once for the rebound, drop is given, step one finds the rebound]

80 / 1 -(3/5) = 80 / (2/5) = 80 * (5/2) = 200

48 / 1 -(3/5) = 48 / (2/5) = 48 * (5/2) = 120

Finally, add the two numbers together and there you have it.

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I couldn't remember that stuff, so I just added the first few terms of (0.6) + (0.6)^2 + (0.6)^3 + ... and saw that it was headed for 1.5 and went from there. Maybe not the way it's supposed to be done, but I bet I could have faked my way to a decent mark on that question.

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Originally posted by smomofo
I couldn't remember that stuff, so I just added the first few terms of (0.6) + (0.6)^2 + (0.6)^3 + ... and saw that it was headed for 1.5 and went from there. Maybe not the way it's supposed to be done, but I bet I could have faked my way to a decent mark on that question.
hahaha, I got that one right and pulled off an 83 on the exam

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nice

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Originally posted by smomofo
I couldn't remember that stuff, so I just added the first few terms of (0.6) + (0.6)^2 + (0.6)^3 + ... and saw that it was headed for 1.5 and went from there. Maybe not the way it's supposed to be done, but I bet I could have faked my way to a decent mark on that question.
This is a correct approach, you just should show that the series converges.

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Find the sum of the first 25 even integers that are larger than 17

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930

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Originally posted by smomofo
930
lets see, lets see

not what i got but i could be mistaken

😕

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Originally posted by Drew L
lets see, lets see

not what i got but i could be mistaken

😕
I got 1050. I did it in groups of 5, 18+20+22+24+26 and found each group starting with 110 sum going up by 50 so it was easy to truncate the series, 110+160+210+260+310= 1050