Vincen wrote:Ten strips of paper are numbered from 1 to 10 and placed in a bag. If three numbers are drawn from the bag at random, what is the probability that the sum of the numbers drawn will be odd?
A. 1/12
B. 5/36
C. 15/36
D. 1/2
E. 11/18
Ways to get an ODD sum:
3 odd numbers
1 odd number, 2 even numbers
Ways to get an EVEN sum:
3 even numbers
1 even number, 2 odd numbers
Notice that the blue outcomes and the red outcomes are perfectly parallel.
Implication:
Since the 10 strips contain an equal number of odd numbers and even numbers, the probability of getting the blue outcomes must be equal to the probability of getting the red outcomes.
Thus:
P(odd sum) = 1/2.
P(even sum) = 1/2.
The correct answer is
D.
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
