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#1
12-25-2010
 USMLE Forums Scout Steps History: 1 + CK Posts: 71 Threads: 26 Thanked 42 Times in 17 Posts Reputation: 52
Bacterial Multiplication Numbers

Hi All,
Total streptococcus - 2 x 102 in the media, how many bacteria there will be after they double six times?
I know this is not difficult but I absolutely forget how to calculate it So little bit explain it not only simple answer.

#2
12-25-2010
 USMLE Forums Scout Steps History: 1+CK+CS Posts: 99 Threads: 12 Thanked 62 Times in 27 Posts Reputation: 72

2*2*2*2*2*2*2=1.28*10 4
#3
12-25-2010
 USMLE Forums Scout Steps History: 1 + CK Posts: 71 Threads: 26 Thanked 42 Times in 17 Posts Reputation: 52

Quote:
 Originally Posted by kundra 2*2*2*2*2*2*2=1.28*10 4
Thank you for such detailed description
Are you kidding?
My question is - technique multiplying, so why 1.28?
#4
12-25-2010
 USMLE Forums Master Steps History: 1+CK+CS Posts: 590 Threads: 31 Thanked 1,227 Times in 410 Posts Reputation: 1251

Quote:
 Originally Posted by deyneko Thank you for such detailed description Are you kidding? My question is - technique multiplying, so why 1.28?
kundra took:
200 doubled six times, so
400, 800, 1600, 3200, 6400, 12800
12800 can also be written as 1.28 x 10^4

kundra did it the faster way:
2x10^2 doubled six times is (2x10^2) x (2^6)
which also comes out to 1.28 x 10^4
#5
12-25-2010
 USMLE Forums Guru Steps History: 1 + CK Posts: 373 Threads: 30 Thanked 374 Times in 160 Posts Reputation: 384

Quote:
 Originally Posted by deyneko Thank you for such detailed description Are you kidding? My question is - technique multiplying, so why 1.28?
The technique is simple......

initial cell count = 2 x 10^2= 200
So in order to double it multiply it by 2.

2 x 2 x 10^2= 2 x200= 400

You want to double it six times, multiple it by 2 six times..

2 x 2 x 2 x 2 x 2 x 2 x 2 x 10 ^2 =128x 10^ 2= 1.28 x 10^4
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 The above post was thanked by: deyneko (12-25-2010)

 Tags Microbiology-, Step-1-Questions

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