Which of the following are/is prime?
I. 143
II. 147
III. 149
(A) II only
(B) III only
(C) I & II
(D) I & III
(E) I, II, & III
The OA is the option B.
Experts, what is the faster way to solve this PS question? I know that 147 is not prime. But how can I determine if (I) or (III) are primes?
Which of the following are/is prime?
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I. 143M7MBA wrote:Which of the following are/is prime?
I. 143
II. 147
III. 149
(A) II only
(B) III only
(C) I & II
(D) I & III
(E) I, II, & III
143 = 11 x 13
So, 143 is NOT prime.
ELIMINATE C, D and E
II. 147
Check the sum of the digits.
1+4+7 = 12
Since 12 is divisible by 3, we know that 147 is divisible by 3
So, 147 is NOT prime.
ELIMINATE A
By the process of elimination, the correct answer is B
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Brent
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Since 143 = 11 x 13, 143 is not a prime.M7MBA wrote:Which of the following are/is prime?
I. 143
II. 147
III. 149
(A) II only
(B) III only
(C) I & II
(D) I & III
(E) I, II, & III
Since 147 = 7 x 21, 147 is not a prime.
149 is a prime since there is no multiplication of two numbers that equals 149 other than 1 x 149.
Answer: B
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prime factors are numbers that are only divisible by one and its self.
Here,
i. 143 =11*13
ii. 147 =7*21
iii. 149=1*149
roman figure iii is an example of prime factors because it has only 2 factors which is 1 and 149.
Answer is b
Here,
i. 143 =11*13
ii. 147 =7*21
iii. 149=1*149
roman figure iii is an example of prime factors because it has only 2 factors which is 1 and 149.
Answer is b
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This is how I did it.
Since 147 is divisible by 3 (because 1+4+7=12 and it is divisible by 3) then I discarded the options (A), (C) and (E).
Now, watching the options (B) and (D) I knew that III is prime. Hence, I only had to check the option I = 143.
But 143=11*13, thus it is not prime.
Therefore, I concluded that B is the correct option.
Since 147 is divisible by 3 (because 1+4+7=12 and it is divisible by 3) then I discarded the options (A), (C) and (E).
Now, watching the options (B) and (D) I knew that III is prime. Hence, I only had to check the option I = 143.
But 143=11*13, thus it is not prime.
Therefore, I concluded that B is the correct option.