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A lock code was product of two numbers, one taken from set A GMAT

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A lock code was product of two numbers, one taken from set A GMAT  [#permalink]

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New post 24 Dec 2018, 23:01
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  45% (medium)

Question Stats:

65% (02:12) correct 35% (01:30) wrong based on 40 sessions

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A lock code was product of two numbers, one taken from set A = {2, 3, 4, 5, 9} and other taken from set B = {1, 2, 6, 7}. If all possible combinations of numbers from set A and set B are checked, what is the probability of opening the lock if entering any multiple of 6 will open the lock?

a) 1/7
b) 3/5
c) 1/2
d) 3/10
e) 7/20
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Re: A lock code was product of two numbers, one taken from set A GMAT  [#permalink]

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New post 24 Dec 2018, 23:18
Nikhitaarorah wrote:
A lock code was product of two numbers, one taken from set A = {2, 3, 4, 5, 9} and other taken from set B = {1, 2, 6, 7}. If all possible combinations of numbers from set A and set B are checked, what is the probability of opening the lock if entering any multiple of 6 will open the lock?

a) 1/7
b) 3/5
c) 1/2
d) 3/10
e) 7/20


So total combinations possible = 20 (5 items of A multiplied by 4 items of B)

Combinations opening the locks must be multiple of 6, so they must be either 6,12,18,24,30,36 and so on

so combinations possible from given set:

2X6, 3X2, 3X6, 4X6, 5X6, 9X6,9X2, so a total of 7 combinations,

Answer is 7/20

E
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Re: A lock code was product of two numbers, one taken from set A GMAT  [#permalink]

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New post 28 Dec 2018, 10:37
Total cases : 5C1*4C1=20 & possible +ve combinations =7 [ (2,6),(3,2),(3,6),(4,6),(5,6),(9,2),(9,6),]
Hence probability= 7/20 .......Ans E
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A lock code was product of two numbers, one taken from set A GMAT  [#permalink]

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New post 28 Dec 2018, 11:12
Nikhitaarorah wrote:
A lock code was product of two numbers, one taken from set A = {2, 3, 4, 5, 9} and other taken from set B = {1, 2, 6, 7}. If all possible combinations of numbers from set A and set B are checked, what is the probability of opening the lock if entering any multiple of 6 will open the lock?

a) 1/7
b) 3/5
c) 1/2
d) 3/10
e) 7/20


the number of possible combinations = 5 elements of A * 4 elements of B = 20 product outcomes

favorable outcomes which are multiples of 6 are (2*6=12), (3*2=6), (3*6=18), (4*6=24), (5*6=30), (9*2=18), (9*6=54) .. so only 7 outcomes

the probability of opening the lock = 7/20

which is E
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A lock code was product of two numbers, one taken from set A GMAT &nbs [#permalink] 28 Dec 2018, 11:12
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A lock code was product of two numbers, one taken from set A GMAT

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