What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and

Question

What is the units digit of  x^3 ?

(1) x is even

(2)  x^3  is between 10 and 100

shameekv1989 · Answer

OhMy  :- Can you please explain how B could be an answer?

i) x is even -> x could be 2,4 -> x^3 = 8, 64 - Multiple values - Not Sufficient

ii) x^3 is between 10 and 100 -> x could be 3 or 4 -> x^3 can be 27 or 64 -> Units digit can be 7 or 4 - Insufficient

Combining i) and ii) x^3 can only be 64 -> Units digit is 4

Hence C should be an answer.

Bunuel · Answer

Edited the OA. It's C, not B.

OhMy · Answer

shameekv1989   Bunuel

You are right guys. sorry, my mistake.

EgmatQuantExpert · Answer

Solution

To find  
We need to determine
 • The units digit of  x^3

Analysing Statement 1  
As per the information given in statement 1, x is even
However, from this information, we cannot determine the exact units digit of x.
 • For example, if x = 2, then units digits of  x^3  is 8
• Alternatively, if x = 4, then units digit of  x^3  is 4

Hence, statement 1 is not sufficient to answer the question.

Analysing Statement 2  
As per the information given in statement 2,  x^3  is between 10 and 100
Hence, value of  x^3  can be either 27 or 64 – but we cannot uniquely determine the exact value of  x^3

Hence, statement 2 is not sufficient to answer the question.

Combining Both Statements Together  
We know  x^3  can be either 27 and 64, and x is also even (means  x^3  is even)
 • Hence,  x^3  is equal to 64 only, and units digit is 4

Thus, option C is the correct answer.

Correct Answer: Option C

fireagablast · Answer

Why is the answer C and not E? It never says that X is an integer. Unless we are to assume that by definition the word "even" implicitly refers to integers.

(2.66)^3 = 18.821. This is an "even" decimal value for instance, but isn't an integer.

What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and

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