One day last month,Suzanna had $128.On each subsequent day she spent half of the money she had. On which day did she have less then $1 remaining?
2007-08-11 08:58:01 · 30 answers · asked by pop princess 4 in Science & Mathematics ➔ Mathematics
64
32
16
8
4
2
1
On the eighth day of this process, she had less than a dollar.
2007-08-11 09:03:00 · answer #1 · answered by nowhereuare 4 · 0⤊ 1⤋
On the 9th day. Just divide each total in half everyday.
1st= 128 6th=4
2nd=64 7th=2
3rd=32 8th=1
4th=16 9th=50 cents
5th=8
2007-08-11 10:47:16 · answer #2 · answered by james w 5 · 0⤊ 0⤋
9thDAY
day 1 128
day 2 64
. 3 32
. 4 16
. 5 8
. 6 4
. 7 2
. 8 1
day 9 $ .50
2007-08-11 09:04:21 · answer #3 · answered by Kenneth H 3 · 0⤊ 0⤋
if i counted right its on the eigth? 128 the first day, 64 on the second, 32 on the third,16 on the fourth,8 on the fifth, 4 on the sixth, 2 on the seventh and one on the eighth oh i guess it is eight days then
2007-08-11 09:04:22 · answer #4 · answered by DONNAGAN 6 · 0⤊ 0⤋
You can always go day by day to get the answer quickly, but if you really are cool, you will use algebra!
We know that after 'n' number of days, she will have < $1 when she has $0.5, or 50 cents. This Sequence can be geometric, and written as follows:
Where 't1' is denoted as 64,
A geometric sequence is defined by:
tn = a*r^(n-1)
0.5 = 64*0.5^(n-1)
0.0078125 = 0.5^(n-1)
log (0.0078125) = n-1(log(0.5))
7 = n-1
n = 8
Therefore, after 8 days, she will have less than $1.
2007-08-11 09:04:32 · answer #5 · answered by de4th 4 · 0⤊ 0⤋
Its more than just a question that would justify who is smarter and such...
I cannot rememebr the formula, so here is the long way
128, 64, 32,16,8,4,2,1,.50
8th day, you dont count the 128 as a day.
2007-08-11 09:01:48 · answer #6 · answered by Dee_Smithers 4 · 0⤊ 1⤋
The 8th day
2007-08-13 12:17:14 · answer #7 · answered by daprofessa15 2 · 0⤊ 0⤋
9th. Just like someone else pointed out above, you need to go to the ninth day, where there is only .50 left.
2007-08-11 09:10:58 · answer #8 · answered by Anonymous · 0⤊ 0⤋
since you didnt say what day of the week she started to spend her money you cant know what day she ended up with less then a dollar
2007-08-11 09:03:57 · answer #9 · answered by george 2 6 · 0⤊ 0⤋
im a 7th grader and i know how to figure out i just dont have the time right now and nice way to cheat!!! jk it 8 days i had this problem on my homework one day and its kinda hard to explain on here but good luck!!'
kiss kiss!!!
2007-08-11 09:01:59 · answer #10 · answered by *Josie* 4 · 1⤊ 1⤋
The 8th day. She would have 50 cents by then
2007-08-11 09:03:46 · answer #11 · answered by Sherlock 6 · 0⤊ 1⤋