The final step in processing a black and white photographic print is to immerse the print in a chemical fixer. THe print is then washed in running water. Under certain conditions, 98% of the fixer in a print will be removed with 15 min of washing. How much of the original fixer would be left after 1 hr of washing?
Please write a geomertic sequence formula with A1, r, and n. Then solve the formula.
2007-04-07 05:11:05 · 5 answers · asked by nsbball07 2 in Science & Mathematics ➔ Mathematics
I just did the work and got .000016% left.
My formula was:
An = 100{(.02)^(1/15)}^n
and plugged in 60 for n. Please verify.
2007-04-07 05:20:57 · update #1
Thnx all who answered..... i got the same answer so I think I'll be okay!
2007-04-07 05:35:16 · update #2
Hi,
You can use STAT on your calculator to find the exponential function if you give it your 2 points. At 0 minutes 100% of fixer is there. After 15 minutes only 2% of fixer is still there. Your points are (0,100) and (15,2). Enter those in L1 and L2 under STAT, then go to STAT, over to CALC and choose ExpReg. Press enter and you get y = 100*.7704338096*x. This is your equation. You can verify the correct points appear in the table for x = 0 and x = 15. After 1 hour or 60 minutes of washing, look at x = 60 in your table. Your y value is so small it's in scientific notation as 1.6 x 10^-5 or .000016% of fixer is still there.
I hope that helps!! :-)
2007-04-07 05:27:23 · answer #1 · answered by Pi R Squared 7 · 0⤊ 1⤋
A(t) = A1(1-r)^(60t/15)
where A(t) is the remaining amount , A1 is the original amount of the fixer in a print and t is the time of washing in hours.
A(t)/A1
= A1(1-r)^(60t/15)/A1
= 0.02^4
= 0.000016% of the original fixer would be left after 1 hr of washing.
2007-04-07 05:28:12 · answer #2 · answered by sahsjing 7 · 0⤊ 0⤋
he way i understand your problem is A1 =100 r- .02, and ne = the number of 15 minute periods that the washn undergoes.
In this case An = 100*.02^n
For 1 hour of washing, n =4
Hence, An = 100*(.02)^4 = 1.6X10-5 = .0016%
2007-04-07 05:38:07 · answer #3 · answered by ironduke8159 7 · 0⤊ 0⤋
the 1st sequence is: S(n) = 20 ( 3^n ), n=0,a million,2,... and because S(9) = 393660, the sequence has 10 phrases in all. the 2nd sequence has a popular term of 5 and ratio between phrases of -3, consequently the sum of the 1st 8 phrases is: 5 ( a million - (-3)^8 ) / ( a million - (-3) ) = -8200
2016-12-08 20:46:35 · answer #4 · answered by Anonymous · 0⤊ 0⤋
shouldnt your n be equal to 4? hahaha.. i dont know..:(( i cant remember this topic :))
:))
what formula did you use?!..
An= A1*r ^( n-1) ?
2007-04-07 05:26:22 · answer #5 · answered by Jami 3 · 0⤊ 1⤋