# Difficult S1 questions..!Watch

#1
Hello here are some stats questions which i need help on, thanks a lot guys in advance!

(1)A class contains 30 children , 18 girls and 12 boys. Four complimentary theatre tickets are distributed at random to the children in the class. What is the probability that:

(a) All four tickets go to girls
(b) Two boys and two girls receive tickets.

(2) How many different 7-digit numbers can be formed from the digits 0,1,2,2,3,3,3. assuming that a number cannot start with 0?

How many of these numbers will end in 0?

From John
0
12 years ago
#2
(1)
12 years ago
#3
1.a. 18/30 X 17/29 X 16/28 X 15/27
b. 18/30 X 12/29 X 17/28 X 11/27 X 4

May be wrong!
0
12 years ago
#4
you need four lots of part b. because there are 4 ways in which 2 girls and 2 boys get tickets
0
#5
Isnt there a way to calculate part (a) and (b) using permutations and combinations.... and i dont understand part (b) do you mind explaining it if you can please...

Thanks
From John
0
12 years ago
#6
Yeah, permutations and combinations is a better way

Okay so all 4 to girls means 18C4
But thats not it because to find the probability you must divide by the unrestricted, which is 30C4, which gives the same answer as above. The 'C' is a calculator button meaning combination as im sure you know,

For part b. it will be 18C2 X 12C2 all divided by the unrestricted 30C4

Hope this helps
0
#7
(Original post by *LEGEND*)
Yeah, permutations and combinations is a better way

Okay so all 4 to girls means 18C4
But thats not it because to find the probability you must divide by the unrestricted, which is 30C4, which gives the same answer as above. The 'C' is a calculator button meaning combination as im sure you know,

For part b. it will be 18C2 X 12C2 all divided by the unrestricted 30C4

Hope this helps

Yeah thats right, but what about question 2 I find that one quite hard...

Thanks
From John
0
6 years ago
#8
doing these exact questions now, felt obliged to say thanks
0
6 years ago
#9
question 2:

0
6 years ago
#10
(Original post by vickyhunt)
doing these exact questions now, felt obliged to say thanks
You found a thread from 2006 to help you out! This must be some sort of record!!
1
6 years ago
#11
(Original post by davros)
You found a thread from 2006 to help you out! This must be some sort of record!!
Yep hahahaha, still on the exercise! If it wasn't for the internet I'd be lost...
Are you any good at stats? - I have one last question to answer which I'm stuck on.

Omg im going to fail so badly
0
6 years ago
#12
(Original post by vickyhunt)
Are you any good at stats? - I have one last question to answer which I'm stuck on.
I wouldn't call it my favourite area of maths, but if you post the question I'm sure someone will volunteer to help
0
6 years ago
#13
Shockingly I solved it! Using a similar example in the text book

I find the questions way too...'wordy'.. its annoying to look at haha
0
6 years ago
#14
(Original post by vickyhunt)
Shockingly I solved it! Using a similar example in the text book

I find the questions way too...'wordy'.. its annoying to look at haha
I know exactly what you mean...sometimes there seems to be more than 1 way to interpret the question, which doesn't help!
0
6 years ago
#15
(Original post by davros)
I know exactly what you mean...sometimes there seems to be more than 1 way to interpret the question, which doesn't help!
yep haha, same with most topics unfortunately
once you understand what the questions actually asking it's moderately easier!
0
6 years ago
#16
(Original post by vickyhunt)
yep haha, same with most topics unfortunately
once you understand what the questions actually asking it's moderately easier!
Have you managed to solve your other S1 problem now with the hints people have given you?
0
6 years ago
#17
Yep!
Just got to keep at it I guess, difficult to keep on top of everything though!
0
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