Question

A mutiple choice test consists 8 questions with each question having 2 possible answers. how many different ways are there to mark the answers?

Answer 1

no more answers

Answer 2

just one more!

Answer 3

Use the product rule.

Answer 4

and it would come up to?

Answer 5

you tell me?

Answer 6

she just wants answers

Answer 7

You have 8 question, and you can answer each question 2 ways, how many total ways can you answer?

Answer 8

16

Answer 9

Nope

Answer 10

its 8 questions and u can answer it 2 different ways which it doubles

Answer 11

If it were just 2 questions with 2 ways to answer, how may ways would there be to fill the test?

Answer 12

2

Answer 13

2^2

Answer 14

Actually that's a bad example. If there were 3 questions with 2 ways to answer each how many ways

Answer 15

I'm not asking you cantor ;p

Answer 16

ok :)

Answer 17

in the same way but just with 3

Answer 18

Lets say it's a true false test with 3 questions.

I can answer

True, True, True
False, True, True
True, False, True
False, False, True
True, True, False
False, True, False
True, False, False
False, False, False

Right?

Answer 19

Yeah I know that

Answer 20

So how many is that?

Answer 21

25

Answer 22

Really? Cuase I only count 8 different ways I can do the test.

Answer 23

Err Cause rather.

Answer 24

theres 8 ways but all toghether theres 25 if u count the true false's

Answer 25

No. There are 8 different possible ways to complete the test.

Answer 26

25 ????????????????

Answer 27

So for your original question if you have 8 questions, how many possible ways can you complete the test?

Answer 28

should i ask ?

Answer 29

if u count them all toghether u get 25 thats how so stop u guys are suppose to help not be mean

Answer 30

sorry i was talking to polpak

Answer 31

w.e bye someone else will help me

Answer 32

Giving you the answer doesn't help you

Answer 33

well when it's done and outta the way I will not have to look back at it so..

Answer 34

except when it's time to take the test, or when something new is taught that uses this to solve, etc.

Answer 35

Everything builds on everything else

Answer 36

ur helping everyone else and giving them answeers?

Answer 37

pol, she added up all of them, she cant count either , there are 24 in that list

Answer 38

Yeah

Answer 39

there's 25

Answer 40

no theres 24

Answer 41

There are 8 lines, with 3 words on each line.

Answer 42

This is one of those things you got someone to tell you and didn't look back about I can see.

Answer 43

i didnt even think of that,

Answer 44

\[8\times 3 \ne 25\]

Answer 45

right

Answer 46

pol, so your integration seems redundant

Answer 47

hrm?

Answer 48

its 2 not 3

Answer 49

You talking about your u-sub question? please ask over there.

Answer 50

well, 8*2 is certainly not 25.

Answer 51

sure

Answer 52

you mean 8 *3

Answer 53

its 16

Answer 54

she cant count and doesnt reason well.

Answer 55

I do mean 8*3, but she claimed it was 2, not 3.

Answer 56

the problem states 3 not 2

Answer 57

wait, i guess theres some subtley here. let me see

Answer 58

2 not 3

Answer 59

Erg. Ok look chika.

I enumerated the possible outcomes for a test with 3 questions where each question had 2 answers.

Answer 60

ok each of those lines is ONE possibility for the test to be solved

Answer 61

Each line in my post was a way you could complete the whole test. Not one question.

Answer 62

so you wrote out the entire sample space

Answer 63

Try something more simple. If you have two true or false questions how many ways can you answer them?

Answer 64

I didn't want to try to write out the sample space for 8 questions because a) that would have given her the answer, and b) I didn't want to write 256 lines.

Answer 65

the other way is to use multiplication rule
for the first question there are 2 ways, second question there are 2 ways to answer, etc,
so the total ways is 2 x 2 x 2 ...

Answer 66

kind of like a tree diagram

Answer 67

so you can enumerate the entire space, as you did pol for your simpler example. or you can use product rule rather than enumerate 256 cases

Answer 68

o wait

Answer 69

I got it

Answer 70

http://www.khanacademy.org/v/probability--part-2?p=Probability

Answer 71

chika, how did you get 25 !!!

Answer 72

i got the answer

Answer 73

pol, it is redundant because you already have cos z dz in the numerator

Answer 74

du = cos z dz, and you already have cos z dz in the numerator