GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 25 Jan 2020, 03:19

### 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

# Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected

Author Message
TAGS:

### Hide Tags

BSchool Forum Moderator
Joined: 29 Jan 2015
Posts: 1475
Location: India
WE: General Management (Consumer Products)
Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected  [#permalink]

### Show Tags

24 Dec 2018, 01:57
00:00

Difficulty:

25% (medium)

Question Stats:

69% (01:05) correct 31% (00:59) wrong based on 59 sessions

### HideShow timer Statistics

Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected at random, what is the probability that both of the bulbs are fine?

(A) (94+95)/(100*99)

(B) (94*95)/(100*99)

(C) 1-(4*5)/(100*99)

(D) (95/100)*(94/100)

(E) (95/100)+(94/100)
Intern
Joined: 23 Jul 2018
Posts: 18
Location: India
GMAT 1: 660 Q48 V32
GPA: 4
WE: Information Technology (Telecommunications)
Re: Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected  [#permalink]

### Show Tags

24 Dec 2018, 06:57
The probability of selecting a non-defective light bulb out of 100: (100-5)/100 = 95/100 --- (i)
The probability of selecting a non-defective light bulb out of remaining 99: (100-6/99) = 94/99 --- (ii)

Therefore, multiplying (i) and (ii),
option B) (94*95)/(100*99)
SVP
Status: It's near - I can see.
Joined: 13 Apr 2013
Posts: 1698
Location: India
GPA: 3.01
WE: Engineering (Real Estate)
Re: Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected  [#permalink]

### Show Tags

19 Mar 2019, 04:45
rohan2345 wrote:
Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected at random, what is the probability that both of the bulbs are fine?

(A) (94+95)/(100*99)

(B) (94*95)/(100*99)

(C) 1-(4*5)/(100*99)

(D) (95/100)*(94/100)

(E) (95/100)+(94/100)

Bunuel : If nothing is given, should we consider that we have "non-replacement" case.
_________________
"Do not watch clock; Do what it does. KEEP GOING."
Re: Of the 100 bulbs in a box, 5 are defective. If two bulbs are selected   [#permalink] 19 Mar 2019, 04:45
Display posts from previous: Sort by