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Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 18:46
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GMATBusters’ Quant Quiz Question 8 For questions from previous quizzes click hereIs m > 0? (1) mn = 15 (2) m + n = 8
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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 18:49
(1) mn= 15 or any positive number it shows either both m and n are positive or both m and n are negative NOT Sufficient (2) m + n= 8 or any positive number It shows at least one of m and n is positive NOT Sufficient Combining Statements 1 & 2, we get both m and n are positive, hence SUFFICIENT Answer C
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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 19:10
1) If m=3 and n=5, then m=3<0. However, if m=3 and n=5, then m=3>0. Therefore, this statement is clearly insufficient. 2) If m=4 and n=12, then m=4<0. However, if m=4 and n=4, then m=4>0. Therefore, this statement is clearly insufficient. 1)+2) from 2): n=8m. Plugging this equation into 1) m(8m)=15 m^28m+15=0 (m3)(m5)=0 here m=3 or m=5. In either case m>0. Sufficient. Answer: C



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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 19:32
is m > 0? (1) mn= 15 (2) m + n= 8 (1) mn = 15 When m=5 , n=3 , then m*n = 15 and m>0 when m=5, n=3 , then m*n = 15 and m<0 Option A not sufficient. (2) m+n = 8 when m=4,n=4 , then m+n = 8 and m >0 when m = 1 , n = 9, then m+n=8 and m<0 Option B is not sufficient Consider (1) + (2) m*n = 15 and m+n = 8 Only possible option to satisfy both condition is M=5,N=3 or M=3,N=5 and in both the case m > 0 Option (C) is the answer Ans C
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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 20:18
Qs: is m > 0?
(1) mn= 15
no information on sign of m & n, both can be negative or positive. m=3, n= 5 then mn= 15, so m is positive , hence m>0 if m =3, n=5, then mn= 15 but m is negative hence m<0 not sufficient to answer the question.
(2) m + n= 8
this state that atleast one of the variable is positive but which one is not clear. or m can be zero also. if m = 2, n=6 then m+n= 8 and m is positive m =2, n= 10, then m+n= 8 and m is negative. not sufficient to answer the question.
combining, we know from statement 2 that atleast one will be positive and from statement 1, that both should be of same sign. therefore both the variable are positive in sign.
therefore m>0 is possible to determine.
Answer is C.



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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 20:20
Is m > 0?
(1) mn= 15 (2) m + n= 8
1) m can be any negative number and in that case if n is also is a negative number, mn can still be equal to an positive number. not sufficient.
2) same as 1, for any negative value of m, n can still cover so that their sum equals to 8. not sufficient.
together, the negative number can be either m or n, which cannot be determined from the information given. not sufficient.
E is the answer.



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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 21:47
m>0? Type : Y/N Statement 1: mn=15 m=3 n=5 gives us Y m=3 n=5 gives us N. Statement 2: m+n=8 m=3 n=5 gives us Y m=5 n=13 gives us N. Combined: mn=15 m+n=8 Therefore n=8m Substituting n=8m in mn=15 m(8m)=15 Gives us a quadratic equation which gives us 2 values of m as 3 and 5. Both are greater than 0. Answer C
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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 22:08
Statement 1: mn=15
m=3, n=5 or m=3,n=5 so in any of the cases we cannot say for sure if m>0, it could be 1,1 3,3,5,5,15,15.
Not Sufficient.
Statement 2: m+n = 8
Here again, since sum is even, so both m and n are either odd or both are even, so some of the possible combinations could be:
2+10 = 8, 3+5 = 8 and etc. So we cannot say for sure, if m > 0. So
Insufficient.
If we combine the 2, we get 2 values of n = 3 and 5, in both cases m will be >0. So,
Answer will be C.



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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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01 Feb 2020, 22:34
(1) or (2) alone is clearly insufficient.
Both together though are sufficient: (1) mn=15: m and n must have same sign (positive or negative) (2) m+n=8: can the sum of two negative (says 3 and 5) be postive? Nah, therefore m>0 always



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Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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02 Feb 2020, 01:15
is m > 0?
(1) mn= 15 (2) m + n= 8 #1 mn= ( 3,5) ( 3,5) ( 15,1) ( 45,1/3) insufficient #2 m+n = 8 ( 8,0) ( 7,1) ( 3,5) .. insufficient from 1 &2 m,n = 3,5 sufficient IMO C




Re: Is m > 0? (1) mn = 15 (2) m + n = 8
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02 Feb 2020, 01:15




