# math

Drew
Posers and Puzzles 15 Jun '07 04:51
1. 15 Jun '07 04:51
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?

ðŸ˜€

for all you smart fellers
2. 15 Jun '07 05:381 edit
320 feet?
3. huckleberryhound
Devout Agnostic.
15 Jun '07 05:43
It's a rubber ball, it won't ravel atall.

unless ravel means something different where you come from. ðŸ˜›
4. 15 Jun '07 06:01
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?

ðŸ˜€

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!)

ðŸ˜‰
5. 15 Jun '07 06:21
Originally posted by smomofo
320 feet?
Horah!

320 feet it is.
6. 15 Jun '07 06:27
Cool. I actually figured that out on my own! Thanks.
7. 15 Jun '07 06:34
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.
8. 15 Jun '07 06:40
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.
9. 15 Jun '07 06:41
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
10. 15 Jun '07 06:56
nice
11. Ponderable
chemist
15 Jun '07 06:58
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.
12. 15 Jun '07 07:03
Find the sum of the first 25 even integers that are larger than 17
13. 15 Jun '07 07:08
930
14. 15 Jun '07 07:10
Originally posted by smomofo
930
lets see, lets see

not what i got but i could be mistaken

ðŸ˜•
15. sonhouse
Fast and Curious
15 Jun '07 12:00
Originally posted by Drew L
lets see, lets see

not what i got but i could be mistaken

ðŸ˜•
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