• 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)

A level Statistics doubt??Post your doubts here!

Messages
2,703
Reaction score
3,939
Points
273
9 diff fruit pies
3 ppl ---- all gets odd no.

List of odd no. 1 3 5 7 _(9 not possible otherwise all will not get pies!)

Now , lets list possible ways the no. can be divided

1st per 2nd per 3rd per

1 3 5

1 5 3

1 7 1

7 1 1

1 1 7

3 1 5

3 3 3


(See that all combinations add to 9)

Now u c ms says:


1 1 7 = 9C1× 8C1× 7C7 (oe)× 3C1 =216 In above table:here c only 1 out of the three cn get 7 pies so 3C1.
1 3 5 = 9C1× 8C3× 5C5(oe)× 3! = 3024 In above table:here c either can hv 5 or 3 or 1 pie in any order so 3!
3 3 3 = 9C3× 6C3× 3C3 (oe) = 1680
In above table:here c its all getting 3 pie n order doesnt matter!
so you add all n get d final ans!
Hope i cud xplain! Though i myself is not much clear abt y we use 3C1 instd of 3! in the first part ...Bt dat was d explanation we were told @class . A little help there with this Alice123 or syed1995 ASTAR or any1!
it because two variables are the same 1 and 1 so only change that can make the difference is 7 so 3C1 shows
this 1 1 7 or
171 or
711
 
Messages
243
Reaction score
198
Points
43
it because two variables are the same 1 and 1 so only change that can make the difference is 7 so 3C1 shows
this 1 1 7 or
171 or
711

Oh so when possibility is 1 5 3 we are doing 3! as d 3 digits are diff ryt!
Thank u!
 
Messages
1,824
Reaction score
949
Points
123
9 diff fruit pies
3 ppl ---- all gets odd no.

List of odd no. 1 3 5 7 _(9 not possible otherwise all will not get pies!)

Now , lets list possible ways the no. can be divided

1st per 2nd per 3rd per

1 3 5

1 5 3

1 7 1

7 1 1

1 1 7

3 1 5

3 3 3


(See that all combinations add to 9)

Now u c ms says:


1 1 7 = 9C1× 8C1× 7C7 (oe)× 3C1 =216 In above table:here c only 1 out of the three cn get 7 pies so 3C1.
1 3 5 = 9C1× 8C3× 5C5(oe)× 3! = 3024 In above table:here c either can hv 5 or 3 or 1 pie in any order so 3!
3 3 3 = 9C3× 6C3× 3C3 (oe) = 1680
In above table:here c its all getting 3 pie n order doesnt matter!
so you add all n get d final ans!
Hope i cud xplain! Though i myself is not much clear abt y we use 3C1 instd of 3! in the first part ...Bt dat was d explanation we were told @class . A little help there with this Alice123 or syed1995 ASTAR or any1!

Repetition is there in part i.

It becomes 3!/2! .. which is 3.
 
Messages
2,703
Reaction score
3,939
Points
273
guys and gals lets use this thread to discuss answers as well 24 hours after the paper
 
Messages
5
Reaction score
3
Points
3
The weights of letters posted by a certain business are normally distributed with mean 20 g. It is
found that the weights of 94% of the letters are within 12 g of the mean.
(i) Find the standard deviation of the weights of the letters.
w11 61 q5(i):(
 
Messages
2,703
Reaction score
3,939
Points
273
The weights of letters posted by a certain business are normally distributed with mean 20 g. It is
found that the weights of 94% of the letters are within 12 g of the mean.
(i) Find the standard deviation of the weights of the letters.
w11 61 q5(i):(
please see the answers posted before
 
Messages
79
Reaction score
29
Points
18
hey guys how do u do OCT/NOV 2011 variant 61 question 5?? my answers are completely different from the mark scheme! :(
 
Messages
70
Reaction score
8
Points
8
add square of all i.e. (48.3^2 + 55.2^2 + . . . 64.1^2) then divide this by 11 then subtract mean^2 and then take square root
its not coming lyk tht ..... the value is coming in negative ... and square root of negative is not possible .... :confused:
 
Top