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Statistics S1B 17/05/2013 Thread

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Awful.

Thought I'd been given the wrong paper altogether. Didn't finish, couldn't finish it if I was given another 90mins.

Hope you all feel better than I do.

Reply 161

suvvie

Original post by t.adur

Q1 on June 13 paper we just sat, the standard deviation stays the same after converting °F to ° C right ?????????
so sd= 15.7 or something like that?

Yep standard deviation remians the same as of course does the mean.

Data you have is not altering, just a conversion applied to each number.

Reply 162

siudesmond2k

That venn diagram question was so weird... Never seen 4 events in a venn diagram before... I drew B in the middle, then F, H and C are all linked to B, but F, H and C are mutually exclusive so F, H and C does not overlap. Don't really know what figures are inside B...

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Reply 163

EmilyC96

Original post by seajamiet

I got a - number so i know im wrong and thinking of it i believe it doesnt change as well.

I got a minus number too like -8.something?

Something similar was asked in June 2010 (q2b) and the answer was that the standard deviation does change.
Still doesn't explain our minus answer though

Reply 164

cbaaa

Paper was ok but made a few stupid mistakes, what were the probability answers?

Reply 165

EmilyC96

Original post by siudesmond2k

Venn diagram? :s-smilie:

Reply 166

Zebrajess

Original post by EmilyC96

I got a minus number too like -8.something?

Something similar was asked in June 2010 (q2b) and the answer was that the standard deviation does change.
Still doesn't explain our minus answer though

If all data is multiplied, standard deviation is also multiplied by that same scale factor.
If all data has a number added to it, standard deviation stays the same.
So you're meant to just multiply the standard deviation, not take away 32.

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Reply 167

seajamiet

Original post by EmilyC96

I got a minus number too like -8.something?

Something similar was asked in June 2010 (q2b) and the answer was that the standard deviation does change.
Still doesn't explain our minus answer though

Yes -8.3 i think.

Reply 168

Will_Is_Martin

Never want to go to a jewellery store again...

Reply 169

maggiehodgson

If you changed all the fs to cs and recalculated the sd, then you've used the formula but not been efficient. What do you think the examiners would do with that?

Reply 170

EmilyC96

Original post by Zebrajess

Of course! damm thats 2 marks down the drain!

Reply 171

Son234

Original post by Zebrajess

Agreed

The standard deviation Is supposed to change by a factor of 5/9

The minus 32 doesn't affect it

This was posted from The Student Room's iPhone/iPad App

Reply 172

TheUndercoverPanda

Original post by siudesmond2k

Yeah I did a diagram with 3 separate rectangles for the 3 mutually exclusive events (F, H, and C) and then an oval going through all three for B.

Reply 173

Zebrajess

Original post by suvvie

Yep standard deviation remians the same as of course does the mean.

Data you have is not altering, just a conversion applied to each number.

That's not right. When in Fahrenheit, the mean was 62 ish. When all the data is converted to Celsius, the values are between 3 and 30 ish, so the mean must change.
This also applies to standard deviation, whist was 19.9 in Fahrenheit, this obviously is too high for values between 3 and 30.

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Reply 174

Son234

Estimate the value of r with a reason? For the first question

What did you guys get?

I stated it stayed the same as changing unit scaling has no affect

I'm actually debating if I'm
Wrong though 2marks

This was posted from The Student Room's iPhone/iPad App

Reply 175

EmilyC96

Original post by TheUndercoverPanda

Yeah I did a diagram with 3 separate rectangles for the 3 mutually exclusive events (F, H, and C) and then an oval going through all three for B.

did i just completely miss out this page or?

Reply 176

Zebrajess

Original post by Son234

That's what I got. The relationship between the values is still the same. (I also had half an hour left at the end of the exam, so converted all the values and checked r on my calculator :P )

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