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Schools: Wharton '16
Posts: 74
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Difficulty:
15%
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Question Stats:
76% (01:04) correct
24%
(01:19)
wrong
based on 1367
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If n is an integer, is n/15 an integer?
(1) 3n/15 is an integer.
(2) 8n/15 is an integer
DS37602.01
(1) 3n/15 is an integer.
(2) 8n/15 is an integer
DS37602.01
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1. 3n/15 = n/5
We know that n is divisible by 5 . Therefore, one of n's prime factors is 5.
We do not know whether or not n is also divisible by 3.
Insufficient
2. 8n/15 = is also an integer
For 8n/15 to be an integer, n must be divisible by 15.
Sufficient
B.
We know that n is divisible by 5 . Therefore, one of n's prime factors is 5.
We do not know whether or not n is also divisible by 3.
Insufficient
2. 8n/15 = is also an integer
For 8n/15 to be an integer, n must be divisible by 15.
Sufficient
B.
I know i got it wrong but can someone please tell me what is wrong with this approach?
Stat 1) 3n/15 is an integer.
=> 3*(n/15) is an integer.
Wont this be only possible if n/15 is an integer?
Stat 1) 3n/15 is an integer.
=> 3*(n/15) is an integer.
Wont this be only possible if n/15 is an integer?
iamgame
Ah. I correct myself...this is also possible for n=5. in that case n/15 is not an integer, given 3n/15 is an integer.
B
stmt1 : 3n/15 is an integer. the multiples of 15 are 3 and 5 and we are given a 3 in 3n. so we know that n at least has a multiple of 5 but we do not know if it contains a multiple of 3. insuff
stmt 2: 8n/15 is an integer. Using the same logic above we need a 3 and a 5. 8 is 2^3 do we know that n has the multiples of 3 and 5 so suff
stmt1 : 3n/15 is an integer. the multiples of 15 are 3 and 5 and we are given a 3 in 3n. so we know that n at least has a multiple of 5 but we do not know if it contains a multiple of 3. insuff
stmt 2: 8n/15 is an integer. Using the same logic above we need a 3 and a 5. 8 is 2^3 do we know that n has the multiples of 3 and 5 so suff
I agree with B.
Question rephrased as is n divisible by 3 and 5?
(1) 3n/15 is integer. Tells us n is divisible by 5 but is insufficient to tell us if n is divisible by 3. INSUFF.
(2) 8n/15 is integer. This is only possible if n is multiple of 15 as 8 does not have any prime factors same as 15. SUFF.
Question rephrased as is n divisible by 3 and 5?
(1) 3n/15 is integer. Tells us n is divisible by 5 but is insufficient to tell us if n is divisible by 3. INSUFF.
(2) 8n/15 is integer. This is only possible if n is multiple of 15 as 8 does not have any prime factors same as 15. SUFF.
sashiim20
Joined: 04 Dec 2015
Last visit: 05 Jun 2024
Posts: 608
Location: India
Concentration: Technology, Strategy
Schools: ISB '19 IIMB IIMA XLRI HEC Sept19 intake Rotman '21 NUS '21 NTU '20 Trinity MBA '20 Bocconi '21 Smurfit "21
WE:Information Technology (Consulting)
Schools: ISB '19 IIMB IIMA XLRI HEC Sept19 intake Rotman '21 NUS '21 NTU '20 Trinity MBA '20 Bocconi '21 Smurfit "21
Posts: 608
Shan30
To find out is \(\frac{n}{15}\) an integer.
(1) \(\frac{3n}{15}\) is an integer
Lets take n = 5
\(\frac{3*5}{15}\) = 1 ----- Integer.
\(\frac{n}{15} = \frac{5}{15} = \frac{1}{3}\) ---------- (Not an integer)
Lets take n = 15
\(\frac{3*15}{15} = 3\)
\(\frac{n}{15} = \frac{15}{15} = 1\) --------- (Integer)
I has multiple values therefore I is Not Sufficient.
(2) \(\frac{8n}{15}\) is an integer
Given \(\frac{8n}{15}\) is an integer.
Factors of 8 are 1,2,4,8.
15 is not a factor of 8. Hence 15 has to be a factor of n.
Therefore \(\frac{n}{15}\) is an integer. ------------ (II is Sufficient)
Answer (B)...
Hope its clear now.
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Posts: 160
ashiima
(1) 3n/15 can be divisible by 3 and the answer will be n/5.
If n/5, it cannot be clearly stated that n/15 is an integer using the reference that n/5.
(2) 8n/15.
If 8n is divisible by 15 then n must be divisible by 15.
Hence, B
If n is an integer, is \(\frac{n}{15}\) an integer?
(1) 3n/15 is an integer.
If 3n/15 is an integer, then n/5 is an integer. This piece of information tells us that is a multiple of 5. Therefore we can't say for sure whether n/15 is an integer. INSUFFICIENT.
(2) 8n/15 is an integer
If 8n/15 is an integer, then we can say with certainty that 8n is a multiple of 15. If 8n is a multiple of 15, we can say n is a multiple of 15. Why? 8 does not share any common factors with 15. Within n, we can guarantee that it has the factors needed. SUFFICIENT.
Answer is B.
(1) 3n/15 is an integer.
If 3n/15 is an integer, then n/5 is an integer. This piece of information tells us that is a multiple of 5. Therefore we can't say for sure whether n/15 is an integer. INSUFFICIENT.
(2) 8n/15 is an integer
If 8n/15 is an integer, then we can say with certainty that 8n is a multiple of 15. If 8n is a multiple of 15, we can say n is a multiple of 15. Why? 8 does not share any common factors with 15. Within n, we can guarantee that it has the factors needed. SUFFICIENT.
Answer is B.
wishmasterdj
Joined: 04 May 2016
Last visit: 25 Oct 2021
Posts: 91
Location: India
Schools: ISB '18 (A)
GMAT 1: 700 Q48 V37
GPA: 3.2
1) 3n/15 is basically the same as n/5, telling us that n is divisible by 5. but not about 15, INSUFFICIENT.
2) 8n/15 is an integer -> since 8 and 15 have no factor in common, thus n must be divisible by 15, So SUFFICIENT
2) 8n/15 is an integer -> since 8 and 15 have no factor in common, thus n must be divisible by 15, So SUFFICIENT
Posts: 22
Condition B.
(8*n/15) is an integer, if this has to be an integer then (n/15) has to be an integer.
Hence B is correct.
Hope it helps !
(8*n/15) is an integer, if this has to be an integer then (n/15) has to be an integer.
Hence B is correct.
Hope it helps !
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