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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # In the biology lab of "Jefferson" High School there are 5.4*10^6 germs

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Math Expert V
Joined: 02 Sep 2009
Posts: 60473
In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  [#permalink]

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Difficulty:   15% (low)

Question Stats: 83% (01:19) correct 17% (01:18) wrong based on 41 sessions

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In the biology lab of "Jefferson" High School there are 5.4*10^6 germs, equally divided among 10,800 Petri dishes. How many germs live happily in a single dish?

A. 100
B. 200
C. 500
D. 1000
E. 5000

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Re: In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  [#permalink]

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Bunuel wrote:
In the biology lab of "Jefferson" High School there are 5.4*10^6 germs, equally divided among 10,800 Petri dishes. How many germs live happily in a single dish?

A. 100
B. 200
C. 500
D. 1000
E. 5000

IMO C

5.4*10^6/ 10800==> 54*10^3/108==> 54000/108= 500
Intern  Joined: 24 Jun 2015
Posts: 10
Re: In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  [#permalink]

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Bunuel wrote:
In the biology lab of "Jefferson" High School there are 5.4*10^6 germs, equally divided among 10,800 Petri dishes. How many germs live happily in a single dish?

A. 100
B. 200
C. 500
D. 1000
E. 5000

IMO Solution = (5.4*10^6) / 10,800 = (54*10^5) / (54* 200) = 10^5 / 200 = 100 * 10^3 / 2*100 = 10^3 / 2 = 1,000 / 2 = 500. IMO 'C'.
Economist GMAT Tutor Representative S
Joined: 06 Aug 2019
Posts: 128
Re: In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  [#permalink]

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Official Explanation

The number of germs in a single dish equals the number of germs divided by the number of dishes. The top of the fraction is given in scientific notation. Changing the bottom to scientific notation will allow you to reduce some annoying 0's and work with more comfortable numbers.

Remember the rule: Maintain the balance between the digit term and the exponential term. If one goes up (↑) by a magnitude of 10, the other must go down (↓) by the same magnitude, and vice versa.

Germs: $$5.4×10^6=54×10^5$$

Dishes: $$10,800=108×10^2$$

Germs per dish: $$\frac{54×10^5}{108×10^2}$$

Note that 54108 can be reduced to $$\frac{1}{2}$$. Thus, the calculation can be reduced to

$$\frac{1}{2}×\frac{10^5}{10^2}=\frac{1}{2}×10^{5−2}=\frac{1}{2}×10^3$$

$$=\frac{10^3}{2}=\frac{1,000}{2}=500$$ germs per dish.

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GMAT 1: 600 Q46 V27 Re: In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  [#permalink]

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Bunuel wrote:
In the biology lab of "Jefferson" High School there are 5.4*10^6 germs, equally divided among 10,800 Petri dishes. How many germs live happily in a single dish?

A. 100
B. 200
C. 500
D. 1000
E. 5000

5.4*1000000 = 5400000 / 10800 = 54000/108 = 500 (Note : 108*5=540 so only 2 zeros will be left)
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You are missing on great learning if you don't know what this is: Project SC Butler Re: In the biology lab of "Jefferson" High School there are 5.4*10^6 germs   [#permalink] 09 Dec 2019, 17:54
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# In the biology lab of "Jefferson" High School there are 5.4*10^6 germs  