Join TSR now and get all your revision questions answeredSign up now
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    Thanks again
    You are welcome.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    You are welcome.
    Mr M can you please quickly explain why -ln(e+1) + ln2 = -ln(e+1)/2)
    and not ln(2/(e+1)) ?
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    Mr M can you please quickly explain why -ln(e+1) + ln2 = -ln(e+1)/2)
    and not ln(2/(e+1)) ?
    They are the same.

    \displaystyle \ln \frac{a}{b}=-\ln \frac{b}{a}

    Use your knowledge of the laws of logarithms to figure out why.
    Offline

    16
    ReputationRep:
    (Original post by Dopey')
    Mr M can you please quickly explain why -ln(e+1) + ln2 = -ln((e+1)/2)
    and not ln(2/(e+1)) ?
    They are the same thing
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    They are the same.

    \displaystyle \ln \frac{a}{b}=-\ln \frac{b}{a}

    Use your knowledge of the laws of logarithms to figure out why.
    Thanks, Im really struggling with permutations and combinations.
    For example this question

    In how many ways can a committee of four men and four women be seated in a row if
    a) they can sit in any positions - which is 8!
    b) no one is seated next to a person of the same sex? < I dont get this?
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    Thanks, Im really struggling with permutations and combinations.
    For example this question

    In how many ways can a committee of four men and four women be seated in a row if
    a) they can sit in any positions - which is 8!
    b) no one is seated next to a person of the same sex? < I dont get this?
    Think of it as 4 double seats containing MF instead of 8 single seats.

    Don't keep adding to this thread - if you have new questions about a different topic make a new thread.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    Think of it as 4 double seats containing MF instead of 8 single seats.

    Don't keep adding to this thread - if you have new questions about a different topic make a new thread.
    Will do, can you please help me finish this and I will create a new thread from now on

    so 4! = 24 options theres something missing, this is a hard topic
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    Will do, can you please help me finish this and I will create a new thread from now on

    so 4! = 24 options theres something missing, this is a hard topic
    Well at the moment you have every man paired with a particular woman ...
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    Well at the moment you have every man paired with a particular woman ...
    I was moving the figures around and I got the right answer but it doesnt apply to any other questions so I think on the off chance its right lol

    I did

    4! x (4! x 2!) = 1152
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    I was moving the figures around and I got the right answer but it doesnt apply to any other questions so I think on the off chance its right lol

    I did

    4! x (4! x 2!) = 1152
    So you have 4! ways to arrange the double seats

    But there are 4! male/female pairings

    And the rows can be populated in 2 different ways

    MF MF MF MF or FM FM FM FM
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    So you have 4! ways to arrange the double seats

    But there are 4! male/female pairings

    And the rows can be populated in 2 different ways

    MF MF MF MF or FM FM FM FM
    Are you saying the Calculation above it right?

    So for this question ill go through your step
    six people are going to travel in a six-seater minibus but only 3 of them can drive. In how many different ways can they seat themselves?

    So If i treat the people who can drive as one

    D CCC

    D= Drive C= Cant drive

    4! ways to arrange the seats
    but there are 3 in who can drive so 3!
    and the seats can be populated in 2!

    so 4! x (6! x 2!) I dont get this at all
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    Are you saying the Calculation above it right?

    So for this question ill go through your step
    six people are going to travel in a six-seater minibus but only 3 of them can drive. In how many different ways can they seat themselves?

    So If i treat the people who can drive as one

    D CCC

    D= Drive C= Cant drive

    4! ways to arrange the seats
    but there are 3 in who can drive so 3!
    and the seats can be populated in 2!

    so 4! x (6! x 2!) I dont get this at all
    That is very wrong. The other two people who are capable of driving can sit in any of the passenger seats.

    How many ways to do it are there if only 1 person of the 6 can drive?
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    That is very wrong. The other two people who are capable of driving can sit in any of the passenger seats.

    How many ways to do it are there if only 1 person of the 6 can drive?
    5! who cant drive = 120 options
    • Community Assistant
    Offline

    19
    ReputationRep:
    (Original post by Dopey')
    5! who cant drive = 120 options
    But 3 people can drive so what is the answer ...
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    But 3 people can drive so what is the answer ...
    5! x 3 = 360 which is the answer but Ill look at another question and I cant understand how to apply the method
 
 
 
Poll
If you won £30,000, which of these would you spend it on?
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

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.