sandy wrote:

Maria removed \(\frac{5}{6}\) of the cookies from a jar, and then Andrea removed \(\frac{3}{5}\) of the remaining cookies from the same jar. Which of the following could NOT be the number of cookies originally in the jar?

Indicate all possible values.

A. 6

B. 15

C. 30

D. 60

E. 200

F. 210

G. 340

Let x = original # of cookies

So, AFTER (5/6)x cookies are removed, there are

x/6 cookies REMAINING.

This tells us that

x must be divisible by 6.

Andrea removed 3/5 of the REMAINING cookies.

So, she removed 3/5 of the x/6 remaining cookies.

(3/5)(x/6) =

x/10So,

x must be divisible by 10So,

x must be divisible by 6 AND by 10Examine the answer choices:

A. 6 NOT divisible by 10.

KEEPB. 15 NOT divisible by 10.

KEEPC. 30 is divisible by 6 AND 10. ELIMINATE

D. 60 is divisible by 6 AND 10. ELIMINATE

E. 200 NOT divisible by 6.

KEEPF. 210 is divisible by 6 AND 10. ELIMINATE

G. 340 NOT divisible by 6.

KEEPAnswer: A, B, E, G

Cheers,

Brent

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Brent Hanneson – Creator of greenlighttestprep.com

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