Last visit was: 22 Nov 2024, 04:04 It is currently 22 Nov 2024, 04:04

Close

GRE Prep 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
Your Progress

every week, we’ll send you an estimated GRE 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.

Close

Request Expert Reply

Confirm Cancel
Verbal Expert
Joined: 18 Apr 2015
Posts: 30003
Own Kudos [?]: 36349 [0]
Given Kudos: 25927
Send PM
avatar
Intern
Intern
Joined: 04 Jun 2018
Posts: 8
Own Kudos [?]: 12 [0]
Given Kudos: 0
Send PM
avatar
Intern
Intern
Joined: 23 Mar 2018
Posts: 7
Own Kudos [?]: 5 [0]
Given Kudos: 0
Send PM
User avatar
Retired Moderator
Joined: 07 Jun 2014
Posts: 4812
Own Kudos [?]: 11194 [0]
Given Kudos: 0
GRE 1: Q167 V156
WE:Business Development (Energy and Utilities)
Send PM
Re: A certain circular stopwatch has exactly 60 second marks and [#permalink]
1
Expert Reply
AnnJoseph wrote:
Can someone please provide a step-wise explanation? Appreciate it!


The stop watch always travels 10 seconds or 10 divisions on the watch. So the final position has to be 10 away from initial position.

Set of all possible initial positions=\(\{1,2,3,.....60\}\) 60 possible positions

If the watch starts at 42 it will stop at 52. Which is within 10 divisions from 53. Start at 41 ends at 51 and so on

So as long as the watch stops at 44 (9 divisions before) or 02 (9 divisions after) the conditions are satisfied. Number of divisions between 44 and 02 is 19.

So for 19 starting positions the condition set in the problem is satisfied!

Probability =\(\frac{19}{60}\)
Verbal Expert
Joined: 18 Apr 2015
Posts: 30003
Own Kudos [?]: 36349 [0]
Given Kudos: 25927
Send PM
A certain circular stopwatch has exactly 60 second marks and [#permalink]
Expert Reply
A certain circular stopwatch has exactly 60 second marks and a single hand. If the hand of the watch is randomly set to one of the marks and allowed to count exactly 10 seconds, what is the probability that the hand will stop less than 10 marks from the 53-second mark?

A. \(\frac{1}{6}\)

B. \(\frac{19}{60}\)

C. \(\frac{1}{3}\)

D. \(\frac{29}{60}\)

E. \(\frac{1}{2}\)
Prep Club for GRE Bot
A certain circular stopwatch has exactly 60 second marks and [#permalink]
Moderators:
GRE Instructor
84 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne