if m =(2^x)*(5^y)*(7^z)

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if m =(2^x)*(5^y)*(7^z)

by amsm25 » Mon May 07, 2012 12:15 am
if m =(2^x)*(5^y)*(7^z) and both 350 and 280 are factors of m. What is the minimum value of xyz?
1)700
2)70
3)24
4)6
5)5


OA- B

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by aneesh.kg » Mon May 07, 2012 12:23 am
If both 350 and 280 are factors of m, m should be able to accomodate all the powers of 2,5 and 7.
Since we have to find the minimum value of x,y and z we will pick the highest powers of 2,5 and 7 from 350 and 280.

350 = (2^1)*(5^2)*(7^1)
280 = (2^3)*(5^1)*(7^1)

max x = 3
max y = 2
max z = 1

so minimum value xyz = 6

[spoiler](D)[/spoiler], IMO.

Let me try to validate this answer.
I am claiming that minimum m = (2^3)*(5^2)*(7^1) = 1400
Are both 350 and 280 factors of m?
YES!

Check OA.
Aneesh Bangia
GMAT Math Coach
[email protected]

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by amsm25 » Mon May 07, 2012 3:02 am
Me too got 6 .... but the OA given in B ... no explanation given ... guess 6 is correct then