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Recent content by Kangxidi
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A level Statistics doubt??Post your doubts here!
The original normal distribution is modelled with a mean PROFIT of 6.4 and the PROFIT's standard deviation = 5.2 How do we call a loss then? Loss is when the profit value is less than 0. Imagine you are buying a can of Pepsi for 3 dollars and sell it for 7 dollars to your friend, your profit... -
A level Statistics doubt??Post your doubts here!
Work out the probability that the company is making a loss. Since loss means a profit that is less than zero, we are working P(X<0) Therefore P(Z < -6.4/5.2) = 1- 0.8909 = 0.1091 <-- probability that it makes a loss. Next step, a loss of exactly 1 out of 4 days can be modelled with... -
Statistics P6 Help needed
Since 8.2 mins is the mean, probability of a visit LESS than 8.2 mins = 0.5 From the question, we can say that X~B(35,0.5) Therefore, X~N(17.5 , 8.75) since np = 35 * 0.5 = 17.5 and npq = 35 * 0.5 * 0.5 = 8.75 :) P(X<16) P(Z<= (15.5-17.5)/8.75^-0.5) and so on :) -
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Statistics P6 Help needed
Are you sure ON10 63 7 iv) ? I dont see why you need to find p or q there..? :o -
A level Statistics doubt??Post your doubts here!
Yes thats for part A I clearly understood it :D thanks! But what about part B? I thought it's asking to have both end sides to be on the same gender? O.o -
A level Statistics doubt??Post your doubts here!
I think I did haha thanks for actually replying :P -
A level Statistics doubt??Post your doubts here!
X~N(20,sd^2) P(20 - 12 < X < 20 + 12) = 0.94 P(8<x<32) = 0.94 From here it's all calculation, see if it is correct. :) -
A level Statistics doubt??Post your doubts here!
I think I read the question of a) wrongly :P But why do we take one side boy and one side girl? I thought both sides should be same gender? -
Statistics P6 Help needed
Any does not matter, as long as you got the logic right ;) -
A level Statistics doubt??Post your doubts here!
*EDIT* star explained it first, we have different approaches :o don't look at mine haha I'm weak in permutations :P a) Imagine you have 4 boys. You will have B B B B And you have 5 girls. It says that you have to make them alternating (BGBGBGBG) and so on, because a boy must be next to a... -
A level Statistics doubt??Post your doubts here!
Yes :) Oh I'm surprised people find the (personally chinese) combination method easier O.o wow glad to see the different approaches :P -
Statistics P6 Help needed
Q3 = 63. Since Q3 is the 75th percentile of data, the probability of anything below Q3 is 0.75 From previous question we know that X~N(51,sd) Therefore P(X<63) = 0.75 z = 0.674 P(Z < (63-51)/sd = 0.674 12 = 0.674 * sd sd = 12/0.674 =17.8 :) -
A level Statistics doubt??Post your doubts here!
Things to note, remember that they are not independent and therefore the probability changes each time, be careful. :) -
A level Statistics doubt??Post your doubts here!
It is very straightforward really, I in fact understand the probability one and can't understand the combination way. :P He took 4 biscuits without replacement. Find that wrapped is EXACTLY 2. Therefore, it can be in .. (W = wrap) (U = unwrap) P(U) * P(W) * P(U) * P(W) Or P(W) * P(U) *...