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Bunuel
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x^3 = n. If the units digit of n is a prime number, then indicate each 31 May 2019, 00:42
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B
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35% (medium)

Question Stats:

64% (01:13) correct 36% (01:08) wrong based on 245 sessions

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x^3 = n. If the units digit of n is a prime number, then indicate each of the following that could be the value of x.

I. 1
II. 8
III. 9

A. I only
B. II only
C. III only
D. I and II only
E. I, II and III
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B
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x^3 = n. If the units digit of n is a prime number, then indicate each 31 May 2019, 01:05
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Bunuel
x^3 = n. If the units digit of n is a prime number, then indicate each of the following that could be the value of x.

I. 1
II. 8
III. 9

A. I only
B. II only
C. III only
D. I and II only
E. I, II and III
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1^3 is 1, 1 is neither prime nor composite.
8^3 is 512, 2 is prime
9^3 is 729, 9 is not prime.

So, II
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x^3 = n. If the units digit of n is a prime number, then indicate each 31 May 2019, 07:22
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Bunuel
x^3 = n. If the units digit of n is a prime number, then indicate each of the following that could be the value of x.

I. 1
II. 8
III. 9

A. I only
B. II only
C. III only
D. I and II only
E. I, II and III
Show more

out of given options x^3=n ; n is prime is possible with x= 8
where n unit digit = will be 2 sufficient
IMO B
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x^3 = n. If the units digit of n is a prime number, then indicate each 01 Jun 2019, 21:52
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Given:

\(x^3\) = n and the units digit of n is a prime number.

Prime numbers have exatcly two factors: 1 and the number itself. Examples of prime numbers are 2 , 3 , 5 , 7 . 11 and so on.

Now, let us check for the given cases

Case I

if x = 1

then \(x^3\) = n = 1 , BUT 1 is not a prime number as 1 has only one factor. Therefore the unit digits of n is not a prime number.

Case I is not possible

Case II

if x = 8

\(x^3\) = n = \(8^3\) = 512 . The units digit of n (2) is a prime number.

Case II is possible

Case III

if x = 9

\(x^3\) = n = \(9^3\) = 729. The units digit of n (9) is not a prime number as it has 3 factors : 1 , 3 , 9

Case III is not possible

So only case II is possible.

The correct answer is B
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x^3 = n. If the units digit of n is a prime number, then indicate each 21 Apr 2025, 22:27
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