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We define that K@J is the product of j number...

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by BTGmoderatorLU » Mon Nov 13, 2017 2:46 pm
We define that K@J is the product of j number from k in increasing order for positive integers K, J. For example, 6@4=6*7*8*9. If A=2020 and B=2120, what is the value of the ratio A/B?

A. 1/2
B. 1/3
C. 2/3
D. 1/4
E. 1/5

The OA is A.

I'm really confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.
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by [email protected] » Mon Nov 13, 2017 10:53 pm
Hi LUANDATO,

This question has a couple of typos in it; I assume that the prompts means to tell us that A = 20@20 and B = 21@20 (so that we can use the 'Symbol' that the question provides to us.

We're asked for the value of A/B...

A = (20)(21).....(38)(39)
B = (21)(22).....(39)(40)

Dividing B into A would allow to 'cancel out' almost every number (21 through 39, inclusive), leaving us with.... 20/40 = 1/2

Final Answer: A

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