|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
21 Mar 2022, 02:45
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
62% (02:32) correct
38%
(02:33)
wrong
based on 298
sessions
History
Date
Time
Result
Not Attempted Yet
In a certain population of microbes in a petri dish, the rate of increase in the population is 9 percent per hour. The time it takes for a given population to double can be estimated using the formula 70/t hours, where t is the rate of increase per hour expressed as a percent. If the number of microbes in the dish is 60,000 at the start of the first hour, what will be the approximate number of microbes after 48 hours?
A. 120,000
B. 420,000
C. 720,000
D. 1,900,000
E. 3,800,000
Are You Up For the Challenge: 700 Level Questions
A. 120,000
B. 420,000
C. 720,000
D. 1,900,000
E. 3,800,000
Are You Up For the Challenge: 700 Level Questions
21 Mar 2022, 18:22
Kudos
Bookmarks
Bunuel
Breaking Down the Info:
\(\frac{70}{t} = \frac{70}{9}\) is the amount of time it takes for the number of microbes to double. We can divide 48 by this to find the number of times we double:
\(48/\frac{70}{9} = \frac{432}{70} \approx 6\). Thus we double more than 6 times.
\(2^6 = 64\), so we expect the answer to be more than \(60,000 * 64 = 3,840,000\).
Answer: E
14 Apr 2025, 00:06
Kudos
Bookmarks
Bunuel
In a period of 70/9 hours, the number of microbes doubles i.e. gets multiplied by 2. In 48 hours, how many such periods are there? There are
\(\frac{48}{70/9} = 6\) (approximately) such periods.
In 6 periods, the number of microbes will become 60k * 2 * 2 * 2 * 2 * 2 * 2 = 60k * 64
This is somewhat more than 3600k and hence the answer is (E)
