Ocr mei statistics 1 exam thread (24/05/13)

Did anyone else get like 14000 for the variance or something like that, 145541 i know it had 14 in the start and it was a big number, not sure if thats right but it did seem like a massive number.

Reply 202

username616640

For the last part of the last question, I got so confused. Was it saying probability of hitting 3 in 6 throws? But if she hits 3 in the first 3, she stops.....so P(B*B*B in first 3) + (If 1B in first 3, 2 in next 3) + (2B in first 3, 1 in next 3)..

e.g.
BBB
BNNBBN
NBNBBN

etc?

Reply 203

Original post by Mahinder

the question with water bottle and tap bottle
The last part was like 46 boxes find the expectation so i did 46 times the answer i got in my last question anyone did the same?

48*0.8684 to get your answer.

Reply 204

juniorx

Original post by juniorx

oh **** looks like i made a mistake then

aaargh i just calculated it now and it is 5.62x10-3. I'm not sure and can't remember if it i put 5.62 or 5.82 :confused:

Reply 205

username616640

Original post by Blobar

Did anyone else get like 14000 for the variance or something like that, 145541 i know it had 14 in the start and it was a big number, not sure if thats right but it did seem like a massive number.

I got that too! I wasn't sure if it was right....

Reply 206

Original post by superxo2

For the last part of the last question, I got so confused. Was it saying probability of hitting 3 in 6 throws? But if she hits 3 in the first 3, she stops.....so P(B*B*B in first 3) + (If 1B in first 3, 2 in next 3) + (2B in first 3, 1 in next 3)..

e.g.
BBB
BNNBBN
NBNBBN

etc?

Nope sorry thats wrong because it said if she hits one in the first 3 throws then she just stops

so

BBB NNNBBB
if it was BNNBBN she'd just stop after BNN

Reply 207

juniorx

Original post by Blobar

48*0.8684 to get your answer.

yeh thats what i did

Reply 208

I almost did it wrong since I carried on from my 50 bags from the previous question so was doing P(X=0) 50C0 (0.9)^50, lucky I had time to go through all the question again and saw my mistake! Phew!

(edited 10 years ago)

Reply 209

tumblrgirl

Original post by Blobar

Did anyone else get like 14000 for the variance or something like that, 145541 i know it had 14 in the start and it was a big number, not sure if thats right but it did seem like a massive number.

yesss i got a number that started with 1455... it was a big number! :tongue:

Reply 210

Attz_09

how did u do your tree diagram and what did subsequently mean i think i got it all wrong haha

Reply 211

Mahinder

omfg i think i got the same as u for the var x

Reply 212

username616640

Original post by Blobar

Nope sorry thats wrong because it said if she hits one in the first 3 throws then she just stops

so

BBB NNNBBB
if it was BNNBBN she'd just stop after BNN

oh!! I misread the question !!

Reply 213

juniorx

Original post by Blobar

Nope sorry thats wrong because it said if she hits one in the first 3 throws then she just stops

so

BBB NNNBBB
if it was BNNBBN she'd just stop after BNN

i nearly made that mistake and wasted 20 mins before i reread the question and actually understood it. :colondollar:

Reply 214