Edexcel S1 - 15th June, 2016 [Exam Discussion]

Yeah same here, i said the exact thing. Not sure if its write thou

SD will not change! SD is root of sum of X - X bar divided by n. So as X- X bar is O is this case so sum of X-X bar do not change! so SD remains the same!

I think we are right for the mean but for the standard deviation, it would decrease because the new value was the same value as the mean therefore there is less deviation in the data set now.

SD will not change! SD is root of sum of X - X bar divided by n. So as X- X bar is O is this case so sum of X-X bar do not change! so SD remains the same!

Ugh I answered the Sarah and Rebecca probability question a really long way around. Multiplimg all the possible options, if I'm incorrect do you think I could lose all 4 marks.
Prob Sarah wins :0.445 and Rebecca 0.46.... Something a,ing those lines.

Sorry haha, I messed up a few questions so it was much easier for me but I do think boundaries wont be lower than 60 for A

Yeah i figured out my mistake. The data would be less varied now so standard deviation would decrease.
I lost two marks for this question i guess?

You're correct in saying that X - X bar stays the same, but n increases by one, so SD decreases.

I calculated Syy in a very complicated way by using the mean to find the sum of x, and the standard deviation to find the sum of x squared and then used the formula I know! Is this OK too for the 1 mark?

Never done a formula for Syy with mean and SD!

I said the mean remains the same, but standard deviation is unchanged!

I didnt put any explanation dosn, do they need explanation for the marks? The question didnt say explain..

I know 0.1 and 0.2 is wrong for P and Q, but can someone tell how many marks I'll lose, cause my working for the rest of q was all right, just used the wrong numbers

Exams are OVER!!!!!!!!!!!!
dreading results day tho

you are most likely an a2 resit, and you're not taking into consideration that the people who use student room are normal a/b grade students and you all forget about the countless numbers of people who will fail this and as there were no easy marks ( box plots) (draw venn diagram) in which people will pick all their marks up on. meaning boundaries will be significantly lower than last years by 2 marks give or take you found it easy because you're either retaking and have had 2 years of stats or you are naturally good at maths and will therefor be park of the a* boundary in which will not affect the other boundaries. so don't be so patronising for the other students by saying that the boundaries will be 64 for an A or definitely won't be sub 60 for an A.

Ugh I answered the Sarah and Rebecca probability question a really long way around. Multiplimg all the possible options, if I'm incorrect do you think I could lose all 4 marks.
Prob Sarah wins :0.445 and Rebecca 0.46.... Something a,ing those lines.