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# AQA MS1B Wednesday 8th June 2016 Exam Discussion Thread watch

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What answer did u get for sd?? i did that tooo
I cant remember but it was definitely correct as I used my graphics calculator
ur 5 e and f are wrong. Question e asked about the diffference of the two which was 2.3 and f u had to do ur answer to the power of 6
Didnt 5e. Say work out the new mean is sd stayed the same and if only 10% were larger than something?

And 5f. Im pretty sure you dont do to the power of 6 only because there was a question in a past paper which was exactly the same as this
3. (Original post by Busted838)
Didnt 5e. Say work out the new mean is sd stayed the same and if only 10% were larger than something?

And 5f. Im pretty sure you dont do to the power of 6 only because there was a question in a past paper which was exactly the same as this
He is right on the first one. I only noticed it when I looked back. It did ask for the difference between the original mean and the reduced one, which was 2.3
4. (Original post by Zedane)
Anyone have any predictions for grade boundaries? It was definetely harder than last years paper imop
I thought it was harder too. I know I messed on a couple of things I'm usually fine with but even so I thought it wasn't very nice - I've not seen many people say they found it easy, so hopefully the boundaries'll be quite low!
5. (Original post by Busted838)

And 5f. Im pretty sure you dont do to the power of 6 only because there was a question in a past paper which was exactly the same as this
I didn't do the power of six as the it said the probability of each bottle not of the box or something like that
6. I'm kicking myself over Q5 where you had to state the difference in the mean. I'd done questions like that before, but for some stupid reason, I didn't realise that I could use 10% as 0.1, even though I've done it a hundred times before.

Pretty upset about this exam to be honest. I was getting mid to high 60's in past papers and I found it tricky and made so many silly mistakes.
7. (Original post by SaltandSugar)
I didn't do the power of six as the it said the probability of each bottle not of the box or something like that
I'm pretty sure it was to the power of 6, as the volume of 1 was normally distributed, so it wanted the probablity of a volume of all 6 in the sample , so
8. How did everyone get 0.891 for 6d?
9. how did you do that binomial one with p as 0.8..? I got 0.0127 which looks wrong but I'm tryna figure out if I'd maybe salvage some working marks :/
10. (Original post by Sirelis)
how did you do that binomial one with p as 0.8..? I got 0.0127 which looks wrong but I'm tryna figure out if I'd maybe salvage some working marks :/
This is all if i remmeber the question corrwct aha

But i think it was p(35 <x <45)
Which is p (×<<44)- p (x <<35)
Cant remeber n but p was 0.8
11. (Original post by Sirelis)
how did you do that binomial one with p as 0.8..? I got 0.0127 which looks wrong but I'm tryna figure out if I'd maybe salvage some working marks :/
The best way would be to do it using the cdf function on your graphical calculator.
12. Probability that more than 35 but less than 45 bands were neither yellow nor white

Thus you have X ~ B(50, 0.8)

For P(35 < X < 45)

Therefore using the complementary event denoted by Y

Y ~ B(50, 0.2)

P(6 ≤ Y ≤ 14) = P(Y≤14) – P(Y≤5) = 0.8913
13. (Original post by TIF141)
One was 166.67 and 200/1.2 = 166.6666...
I Included it because it said 'at most 200' and I rounded to 2dp, but you wouldn't be wrong to exclude it, I wouldn't've thought. Not 100% sure what I did was necessarily right but I suppose if doesn't change whether or not the claim was valid
No, it said - at most 25% less than 200 euros.
14. Ah okay I wasn't so far off then, I did P(X<(or equal to) 15) - P(X<or equal to 4)
(Original post by CirclesAreRound)
Probability that more than 35 but less than 45 bands were neither yellow nor white

Thus you have X ~ B(50, 0.8)

For P(35 < X < 45)

Therefore using the complementary event denoted by Y

Y ~ B(50, 0.2)

P(6 ≤ Y ≤ 14) = P(Y≤14) – P(Y≤5) = 0.8913
15. (Original post by CirclesAreRound)
Probability that more than 35 but less than 45 bands were neither yellow nor white

Thus you have X ~ B(50, 0.8)

For P(35 < X < 45)

Therefore using the complementary event denoted by Y

Y ~ B(50, 0.2)

P(6 ≤ Y ≤ 14) = P(Y≤14) – P(Y≤5) = 0.8913
omg i done exactly that but I got the answer completely wrong! maybe i looked at the wrong probabilities :O
16. I got the first claim as valid , when I converted my CI into euros the number lied inbetween
17. I did this too!
18. (Original post by Dapperblook22)
I'm pretty sure it was to the power of 6, as the volume of 1 was normally distributed, so it wanted the probablity of a volume of all 6 in the sample , so
i agree
19. What about question 3b? I got 0.007.... or something less than 0.01.

And the last question about the claims? The first claim is valid or not?? I just directly multiplied the c.i by 1.20 and said it is valid because 400 is within the new c.i. But some students calculate the new c.i using the mean+-standard error.
The second claim said at most 25% and i got 17.5%, so I said it is invalid because it can not get to 25% as the highest is 17.5%.
20. (Original post by goofyygoober)
What about question 3b? I got 0.007.... or something less than 0.01.

And the last question about the claims? The first claim is valid or not?? I just directly multiplied the c.i by 1.20 and said it is valid because 400 is within the new c.i. But some students calculate the new c.i using the mean+-standard error.
The second claim said at most 25% and i got 17.5%, so I said it is invalid because it can not get to 25% as the highest is 17.5%.
However, for the last question 1st claim is valid, multiplying CI and calculating the new one would give the same answer, so people who calculated the new CI and got different value from yours are wrong. I just modelled a similar question, so this is correct
2nd claim is valid, "at most" suggests anything less than 25 and including 25 itself, your calculation is right though.

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