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# In the expression above, if yn ≠ 0, what is the value of m?

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In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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19 Aug 2019, 01:03
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$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

In the expression above, if yn ≠ 0, what is the value of m?

(1) y = 3n/2
(2) n = 3/2

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Re: In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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19 Aug 2019, 01:03
Bunuel wrote:
$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

In the expression above, if yn ≠ 0, what is the value of m?

(1) y = 3n/2
(2) n = 3/2

Similar question from OG: https://gmatclub.com/forum/in-the-expre ... 44341.html
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In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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Updated on: 19 Aug 2019, 03:50
The most important thing to realize in this question is that it is asking by the value of m, so we need to cancel both y and n so that the given option is SUFFICIENT.

1) y = 3n/2 ---> Let's substitute y by 3n/2 in the given equation:

m=(3/n)/(2/y+1/12y) --->(3/n)/(4/3n+2/36n) ---> (you can keep simplyfing this formula from here, but before doing that you just need to realize that in the numerator we have a fraction with n in the denominator and in the denominator we have a fraction with n in the denominator. That means that regardless of the numbers that the equation will have, at the end, n wil be cancelled ---> SUFFICIENTE

2) n = 3/2 ---> Don't even start substituting because we have no info about y so m will depend on y ---> NO SUFFICIENT

OPTION A

Note that it is very important in DS problems to save most of the time by not doing extra steps. You should quickly relaize in option 1 that n would cancel

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Originally posted by garcmillan on 19 Aug 2019, 03:49.
Last edited by garcmillan on 19 Aug 2019, 03:50, edited 1 time in total.
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Re: In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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19 Aug 2019, 03:49
1
Bunuel wrote:
$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

In the expression above, if yn ≠ 0, what is the value of m?

(1) y = 3n/2
(2) n = 3/2

$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

=> $$m=\frac{3*(2y^2)}{n*(4y+y)}$$ = $$m=\frac{3*(2y^2)}{n*(5y)}$$
=> $$m=\frac{6y}{5n}$$

Statement 1: y = 3n/2

Substitute this in the above eqn.,

=> $$m=\frac{6*1.5*n}{5n}$$
=> $$m=\frac{9}{5}$$

so Statement 1 is SUFFICIENT.

Statement 2: n = 3/2

Substituting this in the eqn.,

=> $$m=\frac{6*y}{5*1.5}$$

we don't know the value of y to determine m.

so Statement 2 is INSUFFICIENT.

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In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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19 Aug 2019, 05:20
1
Bunuel wrote:
$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

In the expression above, if yn ≠ 0, what is the value of m?

(1) y = 3n/2
(2) n = 3/2

Given: $$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

Asked: In the expression above, if yn ≠ 0, what is the value of m?

$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}} = \frac{6y}{5n}$$

(1) $$y = \frac{3n}{2}$$
$$\frac{y}{n} = \frac{3}{2}$$
$$\frac{6y}{5n} = \frac{3}{2} * \frac{6}{5} = \frac{18}{10} = 1.8$$
SUFFICIENT

(2) $$n = \frac{3}{2}$$
Value of y is unknown
NOT SUFFICIENT

IMO A
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Re: In the expression above, if yn ≠ 0, what is the value of m?  [#permalink]

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18 Sep 2019, 01:24
1
Bunuel wrote:
$$m=\frac{\frac{3}{n}}{\frac{2}{y}+\frac{1}{2y}}$$

In the expression above, if yn ≠ 0, what is the value of m?

(1) y = 3n/2
(2) n = 3/2

Video Explanation

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Re: In the expression above, if yn ≠ 0, what is the value of m?   [#permalink] 18 Sep 2019, 01:24
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