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Original post by purplemind
If you have a histogram and you want to find median, do you first change it into grouped frequency table or is there a way you can find it from a histogram?


Grouped frequency table, then you interpolate.
Reply 1301
Sat C1 on Monday 13 - absolutely destroyed it. I finished the paper in 1 hour and had a half-hour left to check through my answers 5+ times and twiddle my thumbs to the point of wanting to leave the exam room out of sheer boredom.
Original post by Revisionbug
Oh okay well some ppl are really helpful but blank me ........ Yes dj im calling u out :cool:


1) I have 7 A Level Maths modules to revise for myself, along with the large Physics exam.
2) I have 3 STEP exams to revise for.

(If you want an actual number, the above 2 points add up to a grand total of 21 and a half hours of exams over this summer, all of which are crammed into the last 2 weeks of June.)

3) Whilst this is potentially contrary to popular belief, I also have a life to live alongside all of this.
4) You put so little effort into writing a question that people can actually read and understand that people will spend as much effort trying to help. If I see a question on this thread which looks like it was typed by a 3 year old then it's a safe bet I'm not going to bother answering it, which is probably why you feel I'm "blanking" you.

I set aside this afternoon to do a STEP II paper in reasonably strict conditions - not perfectly mock-like, but timing each question and so forth. These exam papers determine whether I go to university as both of my choices are dependent on them. I am assuming that you've decided to "call me out" because I didn't immediately respond to your visitor message asking about C3/C4 because I was doing this STEP II paper but regardless of what I was doing at the time I do not see how this is anything other than rude and abrasive, and has achieved nothing more than ensuring that I will remember to ignore you in the future. Have a nice day.
Original post by DJMayes
I also have a life to live alongside all of this.
.

Sure :wink:

Spoiler

Original post by shamika
Could you be any more ridiculous? :eek::confused:

People help voluntarily. You can't expect a random stranger, especially one with his own exams coming up, to be at your beck and call.


Thanks for this. As cited in the above post, I'm not even entirely sure where this is coming from other than the fact I received a visitor message from the poster and didn't respond to it for about an hour because I was doing STEP, even though what I was doing is pretty much tangential anyway.

Original post by joostan
Sure :wink:

Spoiler



Be right back, I need to apply some water to that burn. :tongue:
(edited 10 years ago)
Original post by Boy_wonder_95
Grouped frequency table, then you interpolate.

I don't know what 'interpolate' means.
But I used the fancy formula:
median=b+((n/2-f)/fc)*c
I just don't know how I will remember it for the exam. :lol:
Original post by DJMayes

Be right back, I need to apply some water to that burn. :tongue:


Aloe vera's better :wink:

Spoiler

(edited 10 years ago)
Original post by Felix Felicis
I got x = 5, -1? Is that right? Ceebs working out the y-coordinates but they'll follow


"Ceebs"? Really?
Original post by joostan
Aloe vera's better :wink:

Spoiler



Yeah, but I quote TBBT too often so I decided to try something new. :colone:
Original post by DJMayes
Yeah, but I quote TBBT too often so I decided to try something new. :colone:


Meh. . . You'll be a stand up comic before you know it. :lol:
S2 peeps need more help again :tongue: It's an easy question I just can't quite figure it out, so we have T~U[3,9] (time in minutes elaine takes to check out) part d) Given that Elaine has already spent 4 minutes at the checkout, find the probability that she will take a total of less than 6 minutes to checkout, Now I understand that this just screams conditional probability to me, but what would my denominator be? What does already 4 minutes mean, I thought P(T=4)P(T=4) but then it is a continuous uniform distribution and that would equal 0. Also for my numerator I wouldn't know quite how to progress, P(T<6)nP(4minutes)P(T<6)nP(4 minutes)how would I write this out, cheers guys.

Maybe it is P(T<6P(T4)=P(T<6)P(T4)P(T<6 | P(T\leq 4)=\dfrac{P(T<6)}{P(T\leq 4)} ?
(edited 10 years ago)
Original post by DJMayes
1) I have 7 A Level Maths modules to revise for myself, along with the large Physics exam.
2) I have 3 STEP exams to revise for.

(If you want an actual number, the above 2 points add up to a grand total of 21 and a half hours of exams over this summer, all of which are crammed into the last 2 weeks of June.)

3) Whilst this is potentially contrary to popular belief, I also have a life to live alongside all of this.
4) You put so little effort into writing a question that people can actually read and understand that people will spend as much effort trying to help. If I see a question on this thread which looks like it was typed by a 3 year old then it's a safe bet I'm not going to bother answering it, which is probably why you feel I'm "blanking" you.

I set aside this afternoon to do a STEP II paper in reasonably strict conditions - not perfectly mock-like, but timing each question and so forth. These exam papers determine whether I go to university as both of my choices are dependent on them. I am assuming that you've decided to "call me out" because I didn't immediately respond to your visitor message asking about C3/C4 because I was doing this STEP II paper but regardless of what I was doing at the time I do not see how this is anything other than rude and abrasive, and has achieved nothing more than ensuring that I will remember to ignore you in the future. Have a nice day.


Im srry :frown: i was just stressed overlookin anything even at my own house iv angered everyone except my mum past 2 days i should stop venting on tsr and get some work doneoh and of course write properly again sorry i shouldnt have done that ive been a huge prick the last couple of days
Original post by Robbie242
S2 peeps need more help again :tongue: It's an easy question I just can't quite figure it out, so we have X~U[3,9] (time in minutes elaine takes to check out) part d) Given that Elaine has already spent 4 minutes at the checkout, find the probability that she will take a total of less than 6 minutes to checkout, Now I understand that this just screams conditional probability to me, but what would my denominator be? What does already 4 minutes mean, I thought P(X=4)P(X=4) but then it is a continuous uniform distribution and that would equal 0. Also for my numerator I wouldn't know quite how to progress, P(T<6)nP(4minutes)P(T<6)nP(4 minutes)how would I write this out, cheers guys


Use P(AB)=P(A+B)P(B) P(A|B) = \dfrac{P(A+B)}{P(B)}

A is the event Elaine spends less than 6 minutes at the checkout, B is the event Elaine spends at least 4. You can then work out P(A+B) and P(B) normally from the uniform distribution.

(Alternatively, as four minutes have been spent you can define a new uniform distribution for the amount of time more than four minutes she spends. This isn't necessarily as obvious though.)
Original post by Revisionbug
True im just depressed bout maths atm i guess

Why? :frown:. Maths should make you happy :smile:
Original post by DJMayes
Use P(AB)=P(A+B)P(B) P(A|B) = \dfrac{P(A+B)}{P(B)}

A is the event Elaine spends less than 6 minutes at the checkout, B is the event Elaine spends at least 4. You can then work out P(A+B) and P(B) normally from the uniform distribution.

(Alternatively, as four minutes have been spent you can define a new uniform distribution for the amount of time more than four minutes she spends. This isn't necessarily as obvious though.)


P(A+B) wouldn't it be intersect and surely if it was P(A)+P(B) that would go to 10 ? I was thinking this perhaps?

P(P(T<6)P(T4)=P(T<6)P(T4)P(P(T<6) | P(T\leq 4)=\dfrac{P(T<6)}{P(T\leq 4)} ? A bit lost tbh, cheers dj for any help
(edited 10 years ago)
Original post by Robbie242
S2 peeps need more help again :tongue: It's an easy question I just can't quite figure it out, so we have T~U[3,9] (time in minutes elaine takes to check out) part d) Given that Elaine has already spent 4 minutes at the checkout, find the probability that she will take a total of less than 6 minutes to checkout, Now I understand that this just screams conditional probability to me, but what would my denominator be? What does already 4 minutes mean, I thought P(T=4)P(T=4) but then it is a continuous uniform distribution and that would equal 0. Also for my numerator I wouldn't know quite how to progress, P(T<6)nP(4minutes)P(T<6)nP(4 minutes)how would I write this out, cheers guys.

Maybe it is P(T<6P(T4)=P(T<6)P(T4)P(T<6 | P(T\leq 4)=\dfrac{P(T<6)}{P(T\leq 4)} ?


If she has already spent 4 minutes at the checkout, that means she can't take any less than 4 minutes total, as she's already spent 4 minutes there. In other words, she has to take 4 or more minutes.

Does that help?
Original post by Revisionbug
I'm sorry. :frown: I was so stressed out that I began to overlook everything. Even at my own house, I've made everyone except for my mum irate for the past 2 days. Perhaps I should stop venting on TSR and instead get some work done. Additionally, I should begin writing coherently and unlike a child as you so aptly pointed out :smile:. My apologies for being a huge prick over the last couple of days!


What help do you need? I'll try to, if it's within the range of my abilities. Unfortunately, my answers may be delayed as I'm doing some other stuff :smile:. I've also edited your post in my QUOTE :biggrin:.
(edited 10 years ago)
Original post by justinawe
If she has already spent 4 minutes at the checkout, that means she can't take any less than 4 minutes total, as she's already spent 4 minutes there. In other words, she has to take 4 or more minutes.

Does that help?


So would the denominator be P(T4)?P(T\geq 4)?
Original post by reubenkinara
Why? :frown:. Maths should make you happy :smile:


I flopped the easier maths units and now i have to make full ums in c3 c4 to be safe of getting the grade i want if only i could start this week over oh and the reason i cant write properly is im on a crappy phone it takes me atleast 15 secs to even go bck and click the word or place i want to correct
Original post by purplemind
I don't know what 'interpolate' means.
But I used the fancy formula:
median=b+((n/2-f)/fc)*c
I just don't know how I will remember it for the exam. :lol:


Linear interpolation? Median's gonna be 1/2n so you look in your table what value's the median's going to be between, then you subtract, divide, multiply, then add... but I guess I was taught a different method to you.
(edited 10 years ago)

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