A certain culture of bacteria quadruples every hour. If a container with these bacteria was one-eighth full at 10:00 a.m., at what time was it (1/128)th full?
(A) 9:00 a.m.
(B) 7:00 a.m.
(C) 6:00 a.m.
(D) 4:00 a.m.
(E) 8:00 a.m.
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gmatmachoman
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IOM Egmatmachoman wrote:A certain culture of bacteria quadruples every hour. If a container with these bacteria was one-eighth full at 10:00 a.m., at what time was it (1/128)th full?
(A) 9:00 a.m.
(B) 7:00 a.m.
(C) 6:00 a.m.
(D) 4:00 a.m.
(E) 8:00 a.m.
was that you posting this
x/8 at 10 am;
x/32 at 9 am;
x/128 at 8 am.
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Plug in container = 128.gmatmachoman wrote:A certain culture of bacteria quadruples every hour. If a container with these bacteria was one-eighth full at 10:00 a.m., at what time was it (1/128)th full?
(A) 9:00 a.m.
(B) 7:00 a.m.
(C) 6:00 a.m.
(D) 4:00 a.m.
(E) 8:00 a.m.
Original amount of bacteria = 1/128 * 128 = 1.
Final amount of bacteria = 1/8 * 128 = 16.
After 1 hour, bacteria = 4*1 = 4.
After 2 hours, bacteria = 4*4 = 16.
Since 2 hours are needed, the container was 1/128 full at 10am - 2 = 8am.
The correct answer is E.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
