j_shreyans wrote:
Lake A has a duck population of 30 females and 36 males. Lake B's duck population consists of the same ratio of females to males. If 6 new female ducks are added to Lake B and no other ducks are added or removed, the new total duck population of Lake B could be which of the following?
A)144
B)105
C)78
D)51
E)36
Hi Guru ,
Thanks for your explanation.
One thing is that why do we take multiple of 11 , we are asked to find the total number of duck from Lake B and multiple of 11 comes from Lake A. Pls advise.
According to the prompt:
Lake B's duck population consists of the same ratio of females to males [as Lake A's population].
The words in brackets are omitted, but their presence is implied.
Thus:
(lake B's females : {lake B's males) = (lake A's females) : (lake A's males) = 30:36 = 5:6.
Implication:
In both Lake B and in Lake A, there are 5 females for every 6 males, implying that the total population IN EACH LAKE is a MULTIPLE OF 11.
Also can we solve this question through algebra.
As noted above, the total population in Lake B must be a multiple of 11.
Let the original total population = 11x, where x is an integer greater than 0.
After 6 female ducks are added, we get:
New total population = 11x + 6.
Options for the new total population:
17, 28, 39, 50, 61, 72, 83, 94,
105...
Since it's possible that the new total population = 105, 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
