• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Messages
561
Reaction score
733
Points
103
(20+12<x<20-12)
now you have to imagine the graph in your head, and you have to come into a conclusion that it is symmetrical.

Now imagine the z of 20+12 that is 32 is x
So the z of 20-12 that is 8 will be a negative number -x

Both of them are x but one is negative, because they are the same distance from the mean

Let the probability of x is p
so the probability of -x is 1-p

we know that difference of the two probability is 0.94

so p - (1-p) = 0.94
p - 1 + p = 0.94
2p = 0.95 + 1 = 1.94
p = 0.97

Now is p is 0.97 z is from the table, 1.882 (or 1.881)

now continue normally

1.882 = 32-20 / sd
sd = 12/1.882
=6.38
This was done by Phyzac before:)
littlecloud11
 
Messages
681
Reaction score
1,731
Points
153
7iii) View attachment 21999
As the question states that the argument of z is least, z must represent the lowest possible point in the shaded region. Draw a tangent from the center to the lowest point on the circle (this doesn't have to be accurate) as shown by the blue line. This line represents |z|. The angle between the radius and the tangent is always 90 so a right-angled triangle is formed. The opposite side, with is equal to the radius is 1 unit. The magnitude of complex u is the hypotenuse and the adjacent represents |z|. you can easily find |u|, √(2^2+2^) = √8.
So, |z| =√(√8)^2 -1^2 = √8-1 =√7
Esme
There you go, littlecloud11 have answered this before.
 
  • Like
Reactions: Dug
Messages
971
Reaction score
532
Points
103
YbrtzFh.png


Please help with this. :)
 
Messages
213
Reaction score
135
Points
53
Statistics Paper 6 Question

1. The volume of milk in millilitres in cartons is normally distributed with mean (u) and standard deviation 8. Measurements were taken of the volume in 900 of these cartons and it was found that 225 of them contained more than 1002 millilitres.
(i) Calculate the value of (u)

Can anybody tell me how they found the value of z ?
 
Messages
681
Reaction score
438
Points
73
Messages
4,493
Reaction score
15,418
Points
523
Statistics Paper 6 Question

1. The volume of milk in millilitres in cartons is normally distributed with mean (u) and standard deviation 8. Measurements were taken of the volume in 900 of these cartons and it was found that 225 of them contained more than 1002 millilitres.
(i) Calculate the value of (u)

Can anybody tell me how they found the value of z ?
link
 
Messages
1,824
Reaction score
949
Points
123
HubbaBubba
1. The volume of milk in millilitres in cartons is normally distributed with mean (u) and standard deviation 8. Measurements were taken of the volume in 900 of these cartons and it was found that 225 of them contained more than 1002 millilitres.
(i) Calculate the value of (u)

Can anybody tell me how they found the value of z ?

P(x>1002)=225/900
P(x>1002)=0.25
P(z>1002-u/8)=inversePhi(0.25)
P(z>1002-u/8)=-inversePhi(0.75)
P(z<-(1002-u/8))=-inversePhi(0.75)
-(1002-u)/8=-0.674
1002-u/8=0.674
1002-u=5.392
u=996.6 Answer
 
Top