tens digit please help!

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tens digit please help!

by wawatan » Thu Jul 10, 2008 11:05 pm
13.What is tens digit of the two-digit number x?
1) units digit of x is 7
2) tens digit of 2x is 5

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by Amitk101 » Thu Jul 10, 2008 11:50 pm
I think answer should be B.

If the tens digit of 2x is 5, it means:
x is in range from 25-29.

So tens digit will be 2.

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by target790 » Fri Jul 11, 2008 3:51 pm
what if x is say 75?
then too 2x=2*75=150 has 5 as tenth digit.


I suppose answer is C. When we combine both the statements we get x=27

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by rey.fernandez » Sat Jul 12, 2008 12:45 am
13.What is tens digit of the two-digit number x?
1) units digit of x is 7
2) tens digit of 2x is 5
(1) is clearly not sufficient; no information about the tens digit of x.

(2) tells us that x is either between 25 and 29 inclusive or between 75 and 79 inclusive. Not sufficient because we get two values for the tens digit of x: 2 or 7.

(1&2) tells us that x is either 27 or 77. Still not sufficient as the tens digit of x could be either 2 or 7.

The correct answer is E.
Rey Fernandez
Instructor
Manhattan GMAT

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by vivekverma » Sat Jul 12, 2008 7:47 am
Ans. E

=>One's digit is 7 gives no clue about ten's digit (Ignore)
=> Ten's digit of 2x is 5 gives nothing again .. 2x it can be any number of the form _5_.

Coming 1 and 2 we have x= _7 and 2x=_54
2x can be 154 or just 54 making x 77 or 27 respectively.

No clear solution.

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by tzink » Sat Jul 12, 2008 12:07 pm
Are there tens digit cyclicity rules like there are for unit digits?