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by guerrero » Sun May 12, 2013 4:20 pm
An epidemic is reported to have broken out in Florida. The number of detected instances of a certain disease is reported to have increased by 85% in the last year. What is the lowest number of newly detected instances possible?

(A) 1

(B) 5

(C) 11

(D) 15

(E) 17

OA E
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by GMATGuruNY » Sun May 12, 2013 4:58 pm
guerrero wrote:An epidemic is reported to have broken out in Florida. The number of detected instances of a certain disease is reported to have increased by 85% in the last year. What is the lowest number of newly detected instances possible?

(A) 1

(B) 5

(C) 11

(D) 15

(E) 17

OA E
Let x = the OLD number of instances.
Since the number of instances increases by 85%, the number of NEW instances = (85/100)x = (17/20)x.
Since the number of new instances must be an integer, the minimum value of x = 20.
Thus, the minimum number of NEW instances = (17/20)20 = 17.

The correct answer is E.
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by ranjeet75 » Mon May 13, 2013 7:33 am
[quote="GMATGuruNY"][quote="guerrero"]An epidemic is reported to have broken out in Florida. The number of detected instances of a certain disease is reported to have increased by 85% in the last year. What is the lowest number of newly detected instances possible?

(A) 1

(B) 5

(C) 11

(D) 15

(E) 17

OA [spoiler]E[/spoiler][/quote]

Let x = the OLD number of instances.
Since the number of instances increases by 85%, the number of NEW instances = (85/100)x = (17/20)x.
Since the number of new instances must be an integer, the minimum value of x = 20.
Thus, the minimum number of NEW instances = (17/20)20 = 17.

The correct answer is [spoiler]E[/spoiler].[/quote]

If x = old no. of instances and the instances increased by 85%,
so, no. of new instances = (185/100)*x

Where am I wrong? Please clarify.[/b]
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by sidceg » Mon May 13, 2013 9:27 am
ranjeet75 wrote:
GMATGuruNY wrote:
guerrero wrote:An epidemic is reported to have broken out in Florida. The number of detected instances of a certain disease is reported to have increased by 85% in the last year. What is the lowest number of newly detected instances possible?

(A) 1

(B) 5

(C) 11

(D) 15

(E) 17

OA E
Let x = the OLD number of instances.
Since the number of instances increases by 85%, the number of NEW instances = (85/100)x = (17/20)x.
Since the number of new instances must be an integer, the minimum value of x = 20.
Thus, the minimum number of NEW instances = (17/20)20 = 17.

The correct answer is E.
If x = old no. of instances and the instances increased by 85%,
so, no. of new instances = (185/100)*x

Where am I wrong? Please clarify.[/b]
Percentage increase means [(New - Old)/Old]*100

Hence it should be [(185-100)/100]*x and not (185/100)*x.
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