GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 19 Jan 2019, 00:42

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

## Events & Promotions

###### Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• ### Free GMAT Strategy Webinar

January 19, 2019

January 19, 2019

07:00 AM PST

09:00 AM PST

Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
• ### FREE Quant Workshop by e-GMAT!

January 20, 2019

January 20, 2019

07:00 AM PST

07:00 AM PST

Get personalized insights on how to achieve your Target Quant Score.

# A certain store sells small, medium, and large toy trucks i

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 17 Mar 2014
Posts: 415
Re: A certain store sells small, medium, and large toy trucks i  [#permalink]

### Show Tags

21 Jul 2018, 14:33
Marcab wrote:
fozzzy wrote:
A certain store sells small, medium, and large toy trucks in each of the colors red, blue green, and yellow. The store has an equal number of trucks of each possible color-size combination. If Paul wants a medium, red truck and his mother will randomly select one the trucks in the store, what is the probability that the truck she selects will have at least one of the two features Paul wants?

A. 1/4
B. 1/3
C. 1/2
D 7/12
E. 2/3

let there be x number of trucks of all possible color-size combination.
probability that the truck she selects will have at least one of the two features Paul wants can be found by subtracting the probability of selecting a truck that doesn't has either of the property i.e. it is neither red in color nor of medim size from 1.

In the diagram attached, the I crossed off all the desired results i.e. cancelled all the possible combination of red-medium.
# of remaining outcomes= # of blue circles = # of trucks that don't have either of the desired property.

No. of colors=4
no. of sizes=3
Total outcomes=12

Remaining outcomes=6
hence probability that truck is neither red nor of medium size is $$6/12$$.
hence probability that the truck she selects will have at least one of the two features Paul wants will be $$1 - 6/12$$ or $$1/2$$
+1C

never thought of table usage for probability . Good strategy.
Intern
Joined: 19 May 2018
Posts: 17
Re: A certain store sells small, medium, and large toy trucks i  [#permalink]

### Show Tags

21 Sep 2018, 21:38
Technically the question doesn't specify the # of trucks... only that there is an equal colour/size combo... we are free to make a simple assumption i.e. 3 sizes * 4 colours = 12 trucks

Probability of at least red or medium = probability of a red truck OR probability of a medium truck
P(R) + P(M) - P(RM) ***remember to watch out for double counting the red and medium truck here (trap answer E)
3/12 + 4/12 - 1/12 = 6/12 = 1/2

Re: A certain store sells small, medium, and large toy trucks i &nbs [#permalink] 21 Sep 2018, 21:38

Go to page   Previous    1   2   [ 22 posts ]

Display posts from previous: Sort by