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magical cook
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Can anyone solve and explaing the attached question??? Thank you!!!!
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Source: Beat The GMAT — Problem Solving |
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gamemaster
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This probelm is straight forward once you get used to the notation.
What is give is the following:
Xo = 3
X1 = 2
and you are asked to soved for X3 = 2(X2) - 0.5*X1
Therefore, X3 = 2(x2) - 0,5*(2)
You need to determine the value for X2 which will be
X2 = 2(2) - 0.5(3) = 4 - 1.5 = 2.5 or 5/2
Pluging this vlaue for X3 we get X3 = 2(5/2) - 0.5*2 = 5 -1 = 4
So answer C.
What is give is the following:
Xo = 3
X1 = 2
and you are asked to soved for X3 = 2(X2) - 0.5*X1
Therefore, X3 = 2(x2) - 0,5*(2)
You need to determine the value for X2 which will be
X2 = 2(2) - 0.5(3) = 4 - 1.5 = 2.5 or 5/2
Pluging this vlaue for X3 we get X3 = 2(5/2) - 0.5*2 = 5 -1 = 4
So answer C.
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BTGmoderatorRO
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from the question, we have been given an expression for Xn with n taking to be greater or equal to 2.
to solve for X3, we substitute n=3 in to the expression given.
given: X0=3 and X1=2.
we have, X3=2* X2 - 0.5* X1
solving for X2= 2* X1 -0.5* Xo
X2= (2*2) - (0.5*3)
=4-1.5
=2.5
solving for X3= 2* X2 - 0.5* X1, we have
X3= (2*2.5) - (0.5*2)
= 5-1
=4
look so easy right. Look for more question with related notations in the form of this question and get it solved using this approach.
to solve for X3, we substitute n=3 in to the expression given.
given: X0=3 and X1=2.
we have, X3=2* X2 - 0.5* X1
solving for X2= 2* X1 -0.5* Xo
X2= (2*2) - (0.5*3)
=4-1.5
=2.5
solving for X3= 2* X2 - 0.5* X1, we have
X3= (2*2.5) - (0.5*2)
= 5-1
=4
look so easy right. Look for more question with related notations in the form of this question and get it solved using this approach.
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Hi All,
This question is an example of a sequence question (in which you're given the 'formula' for a sequence of numbers and then asked to find a particular term in the sequence). While this prompt certainly 'looks' complex, it's based on some fairly straight-forward math - and you just have to work through the required arithmetic to get to the correct answer.
In basic terms, this sequence tells us that each 'term' (after the first two terms) is equal to "2 times the prior term minus 1/2 times the term that's 'two terms' prior." We're told that the first term is 3 and the second term is 2.
Thus, we can figure out the third term:
(2)(2) - (1/2)(3) = 4 - 1.5 = 2.5
And then we can figure out the fourth term:
(2)(2.5) - (1/2)(2) = 5 - 1 = 4
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
This question is an example of a sequence question (in which you're given the 'formula' for a sequence of numbers and then asked to find a particular term in the sequence). While this prompt certainly 'looks' complex, it's based on some fairly straight-forward math - and you just have to work through the required arithmetic to get to the correct answer.
In basic terms, this sequence tells us that each 'term' (after the first two terms) is equal to "2 times the prior term minus 1/2 times the term that's 'two terms' prior." We're told that the first term is 3 and the second term is 2.
Thus, we can figure out the third term:
(2)(2) - (1/2)(3) = 4 - 1.5 = 2.5
And then we can figure out the fourth term:
(2)(2.5) - (1/2)(2) = 5 - 1 = 4
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
