Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    12
    ReputationRep:
    Two unbiased tetrahedral dice each have four faces numbered 1, 2, 3 and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
    Sol. I got 37.5 by finding the prob and multiplying by 200 that's 3/16*200
    As it says Expected number so can we write 38 or 37. Will that be correct or we just have to leave the answer as 37.5 without rounding?
    • Study Helper
    Offline

    13
    (Original post by kundanad)
    Two unbiased tetrahedral dice each have four faces numbered 1, 2, 3 and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
    Sol. I got 37.5 by finding the prob and multiplying by 200 that's 3/16*200
    As it says Expected number so can we write 38 or 37. Will that be correct or we just have to leave the answer as 37.5 without rounding?
    What's your working for getting the 3/16 (which is incorrect)?

    Edit: See below.
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by ghostwalker)
    What's your working for getting the 3/16 (which is incorrect)?
    Oh really. I did by first finding the sum. It says the sum is 7 or more so there is 2 'seven' and 1 'eight' from the outcomes and got prob 3/16.
    Thats not right then but the answer I got is right. What is the correct way?
    • Study Helper
    Offline

    13
    (Original post by kundanad)
    Oh really. I did by first finding the sum. It says the sum is 7 or more so there is 2 'seven' and 1 'eight' from the outcomes and got prob 3/16.
    Thats not right then but the answer I got is right. What is the correct way?
    Doh! I missed the "or more" bit. 3/16 is correct.

    I would leave it as 37.5, the expectaction of the number of times.
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by ghostwalker)
    Doh! I missed the "or more" bit. 3/16 is correct.

    I would leave it as 37.5, the expectaction of the number of times.
    Oh okay. Thanks. Does marks be reduced if rounded?
    • Study Helper
    Offline

    13
    (Original post by kundanad)
    Oh okay. Thanks. Does marks be reduced if rounded?
    Sorry, can't comment on markschemes.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Did TEF Bronze Award affect your UCAS choices?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.