 It is currently 23 Nov 2020, 07:50 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # A certain tin contains exactly 10 identically shaped gumdrop  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Founder  Joined: 18 Apr 2015
Posts: 13874
GRE 1: Q160 V160 Followers: 313

Kudos [?]: 3671 , given: 12885

A certain tin contains exactly 10 identically shaped gumdrop [#permalink]
Expert's post 00:00

Question Stats: 78% (01:01) correct 21% (00:58) wrong based on 37 sessions
A certain tin contains exactly 10 identically shaped gumdrops, of which 2 are cherry, 2 are lemon, 2 are grape, 2 are cinnamon and 2 are strawberry. If 2 gumdrops are randomly selected, one at a time and without replacement, what is the probability that the second gumdrop is the same flavor as the first?

A. $$\frac{1}{45}$$

B. $$\frac{1}{25}$$

C. $$\frac{1}{9}$$

D. $$\frac{1}{5}$$

E. $$\frac{2}{5}$$
[Reveal] Spoiler: OA

_________________ VP Joined: 20 Apr 2016
Posts: 1302
WE: Engineering (Energy and Utilities)
Followers: 22

Kudos [?]: 1340  , given: 251

Re: A certain tin contains exactly 10 identically shaped gumdrop [#permalink]
2
KUDOS
Carcass wrote:
A certain tin contains exactly 10 identically shaped gumdrops, of which 2 are cherry, 2 are lemon, 2 are grape, 2 are cinnamon and 2 are strawberry. If 2 gumdrops are randomly selected, one at a time and without replacement, what is the probability that the second gumdrop is the same flavor as the first?

A. $$\frac{1}{45}$$

B. $$\frac{1}{25}$$

C. $$\frac{1}{9}$$

D. $$\frac{1}{5}$$

E. $$\frac{2}{5}$$

Here,
for the first draw we pick any gumdrop,

Now we have remaining 9 gumdrop and selection a matching flavor with the first one = $$\frac{1}{9}$$
_________________

If you found this post useful, please let me know by pressing the Kudos Button

Rules for Posting

Got 20 Kudos? You can get Free GRE Prep Club Tests

GRE Prep Club Members of the Month:TOP 10 members of the month with highest kudos receive access to 3 months GRE Prep Club tests

Intern Joined: 21 Nov 2018
Posts: 21
Followers: 0

Kudos [?]: 5 , given: 1

Re: A certain tin contains exactly 10 identically shaped gumdrop [#permalink]
We also need to calculate the probability of selecting the 1st gumdrop , which will be 1/5 for any gumdeop and then multiply the probability of selecting the 2nd gumdrop , which should be 1/9.
To make it clear would you have also ignored the probability of selecting the 1st gumdrop if the numbers would have been different ? Supreme Moderator
Joined: 01 Nov 2017
Posts: 371
Followers: 12

Kudos [?]: 184  , given: 4

Re: A certain tin contains exactly 10 identically shaped gumdrop [#permalink]
3
KUDOS
Expert's post
kunalkmr62 wrote:
We also need to calculate the probability of selecting the 1st gumdrop , which will be 1/5 for any gumdeop and then multiply the probability of selecting the 2nd gumdrop , which should be 1/9.
To make it clear would you have also ignored the probability of selecting the 1st gumdrop if the numbers would have been different ?

No...

You can choose any of the first so 10/10, the second has to be a pair of this so1/9
Total 10/10*(1/9)=1/9..

If we take the way you have taken..
Then you are calculating ways to pick up a specific gumdeop..
So (2/10)*(1/9)...
But the one you choose can be any of five so 5C1..
So 5C1*(1/5)(1/9)=5*(1/5)(1/9)=1/9
_________________

Some useful Theory.
1. Arithmetic and Geometric progressions : https://greprepclub.com/forum/progressions-arithmetic-geometric-and-harmonic-11574.html#p27048
2. Effect of Arithmetic Operations on fraction : https://greprepclub.com/forum/effects-of-arithmetic-operations-on-fractions-11573.html?sid=d570445335a783891cd4d48a17db9825
3. Remainders : https://greprepclub.com/forum/remainders-what-you-should-know-11524.html
4. Number properties : https://greprepclub.com/forum/number-property-all-you-require-11518.html
5. Absolute Modulus and Inequalities : https://greprepclub.com/forum/absolute-modulus-a-better-understanding-11281.html Re: A certain tin contains exactly 10 identically shaped gumdrop   [#permalink] 24 Nov 2018, 06:31
Display posts from previous: Sort by

# A certain tin contains exactly 10 identically shaped gumdrop  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.