Math As and A2 help

[madan159]

this question is of statistics P6

Find the total number of different 6-digits numbers that can be formed by using the digits 3, 4, 4, 5, 5, 6, 7 .
if one of the digits is picked at random, find the probability that
(a) the number is odd,
(b) the number has two digits 5.

 

[destined007]

7P6/2!2!=1260

a)odd numbers:2x6P5/2!2! + 2x6P5/2!
=360+720=1080
P(x)=1080/1260= 6/7

b)numbers with out two 5s= 6P5/2!
numbers with two 5s= 1260-360=900
P(x)=900/1260=5/7

this is what i think should be the answers. I am not sure so tell me if this is correct.

 

[madan159]

But the exact answer is 360.

 

[destined007]

which part?
If you just tell me the answers that will be helpful.

 

[madan159]

would anyone do Q.No.10(iii) :Yahoo!:

 

[darkpichu]

I've solved the P3 Question.

 

[destined007]

Another way of solving this:

 

[madan159]

help me for part (II)

 

[NehaKush]

find arg of u.. and multiply it by 2

 

[slayers]

have Question Please solve it with Explanation..

A mother has found that 20% of the children who accepts the invitation to her children's birthday parties do not come.
For a Particular party she invites 12 children but only has 10 party hats.
1) What is the Probability that there is not a hat for every child who comes to the party ? [ans :0.275]
The Mother Knows that there is a probability of 0.1 that a children who comes to a party will refuse to wear a hat.
2) If this is taken into account,What is the Probability that there will not be a hat for every child who wants one ? [ans:0.110]

I have posted it in various thread and i got answer from none...this is my last hope..........

 

[slayers]

please Solve this............

1) Two Events A and B such that p(A)=3/4 p(B|A)=1/5 and P(B'|A')=4/7 Find
b) P(B) [ ans=9/35 ]