If y = 2 + 2K and yâ‰ 0yâ‰ 0, then 1/y + 1/y + 1/y + 1/y = ?

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Fri Jan 04, 2019 6:25 am

BTGmoderatorDC wrote:If y = 2 + 2k and y â‰ 0, then 1/y + 1/y + 1/y + 1/y = ?

A. 1/(8+8k)
B. 2/(1+k)
C. 1/(8+k)
D. 4/(8+k)
E. 4/(1+k)

Given: y = 2 + 2k
Rewrite as: y/1 = (2 + 2k)/1
Flip both fractions to get: 1/y = 1/(2 + 2k)

So, 1/y + 1/y + 1/y + 1/y = 1/(2 + 2k) + 1/(2 + 2k) + 1/(2 + 2k) + 1/(2 + 2k)
= 4/(2 + 2k)
= 4/(2)(1 + k)
= 2/(1 + k)

Answer: B

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Quote

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pm; Location: New York, NY; Thanked: 13060 times; Followed by:1906 members; GMAT Score:790

by GMATGuruNY » Fri Jan 04, 2019 6:56 am

BTGmoderatorDC wrote:If y = 2 + 2K and y â‰ 0, then 1/y + 1/y + 1/y + 1/y = ?

A. 1/(8+8k)
B. 2/(1+k)
C. 1/(8+k)
D. 4/(8+k)
E. 4/(1+k)

Let k=0, implying that y = 2 + 2*0 = 2.
Plugging y=2 into 1/y + 1/y + 1/y + 1/y, we get:
1/2 + 1/2 + 1/2 + 1/2 = 2.
The correct answer must yield a value of 2 when k=0.
Only B works:
2/(1+k) = 2/(1+0) = 2.

The correct answer is B.

Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

Quote

fskilnik@GMATH: GMAT Instructor; Posts: 1449; Joined: Sat Oct 09, 2010 2:16 pm; Thanked: 59 times; Followed by:33 members

by fskilnik@GMATH » Fri Jan 04, 2019 9:40 am

BTGmoderatorDC wrote:If y = 2 + 2K and y â‰ 0, then 1/y + 1/y + 1/y + 1/y = ?

A. 1/(8+8k)
B. 2/(1+k)
C. 1/(8+k)
D. 4/(8+k)
E. 4/(1+k)
Source: GMAT Prep

$$\left. \matrix{
y = 2\left( {k + 1} \right) \hfill \cr
?\,\,:\,\,\,4\left( {{1 \over y}} \right) = {4 \over y}\,\, = f\left( k \right)\,\,\,\,\, \hfill \cr} \right\}\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,\,? = {4 \over {2\left( {k + 1} \right)}} = {2 \over {k + 1}}$$

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.

Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br

Quote

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pm; Location: Palo Alto, CA; Thanked: 2867 times; Followed by:511 members; GMAT Score:800

by [email protected] » Fri Jan 04, 2019 10:23 am

Hi All,

We're told that Y = 2 + 2K and Y â‰ 0. We're asked for the value of 1/Y + 1/Y + 1/Y + 1/Y. This question can be solved in a number of different ways, including by TESTing VALUES. Since we're adding four fractions with the SAME denominator, we can just use some basic Arithmetic and Algebra rules.

To start, when adding fractions with the same denominator, we add the numerators. For example

1/5 + 1/5 + 1/5 = 3/5

Here, we're adding 1/Y + 1/Y + 1/Y + 1/Y, so we end up with 4/Y. We're told that Y = (2 + 2K). Substituting that value in, we get...

4/(2+2K)

We can then simplify that fraction, giving us...

2/(1+K)

Final Answer: B

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Quote

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Fri Feb 01, 2019 5:40 pm

BTGmoderatorDC wrote:If y = 2 + 2K and y â‰ 0, then 1/y + 1/y + 1/y + 1/y = ?

A. 1/(8+8k)
B. 2/(1+k)
C. 1/(8+k)
D. 4/(8+k)
E. 4/(1+k)

OA B

Source: GMAT Prep