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Mathematics 7 Online
zarkam21 (zarkam21):

Help please

OpenStudy (linn99123):

with?

zarkam21 (zarkam21):

OpenStudy (michele_laino):

each time 2 outcomes are possible, namely head and tail

zarkam21 (zarkam21):

so 8 outcomes right?

OpenStudy (michele_laino):

yes!

zarkam21 (zarkam21):

so for part one, it would be 2*2*2*2=8?

zarkam21 (zarkam21):

now for part 2

OpenStudy (michele_laino):

please wait: it is 2*2*2*2=16

zarkam21 (zarkam21):

yeah but isn't it a total of 8 outcomes

OpenStudy (michele_laino):

more precisely: we have 2 possible outcomes for each flip, so when we multiply, we get: \[\Large 2 \times 2 \times 2 \times 2 = 16\] that number expresses the possible outcomes

OpenStudy (michele_laino):

if we add: 2+2+2+2 we get 8 nevertheless that number is not interesting for your exercise

zarkam21 (zarkam21):

okay so 2*2*2*2=16 :]

OpenStudy (michele_laino):

correct! I'm sorry for my previous error

zarkam21 (zarkam21):

It is alright!

zarkam21 (zarkam21):

Let's move on to part II

OpenStudy (michele_laino):

ok!

OpenStudy (michele_laino):

here we have to do the subsequent reasoning: lets suppose to start from a head (H) then the next flip can be another head or a tail, so we have these outcomes: \[\Large \begin{gathered} HH \hfill \\ HT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

Yes

OpenStudy (michele_laino):

whereas if we start from a tail (T), then next flip can be another tail or a head, so we get these other possible outcomes: \[\Large \begin{gathered} TH \hfill \\ TT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

okay

OpenStudy (michele_laino):

in total we got these four outcomes: \[\Large \begin{gathered} 1)HH \hfill \\ 2)HT \hfill \\ 3)TH \hfill \\ 4)TT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

So that is part II? HH,HT, TH, and TT

OpenStudy (michele_laino):

no, we have to finish :)

zarkam21 (zarkam21):

okay

OpenStudy (michele_laino):

next, let's start from the outcome 1) then next flip can be a head or a tail, so we get these outcomes: \[\Large \begin{gathered} HHH \hfill \\ HHT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

okay

OpenStudy (michele_laino):

now, let's start from outcome 2), then next flip can be a head ot a tail, so we get these new outcomes: \[\Large \begin{gathered} HTH \hfill \\ HTT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

Yes, :} Would the next be, THH and THT

OpenStudy (michele_laino):

correct!

zarkam21 (zarkam21):

and I'm guessing the next is TTH and TTT

OpenStudy (michele_laino):

and the next two new outcomes are: \[\Large \begin{gathered} TTT \hfill \\ TTH \hfill \\ \end{gathered} \] since I have started from outcome 4)

zarkam21 (zarkam21):

Does it matter what order?

OpenStudy (michele_laino):

no, the order of the outcomes, is not important so, in total we got these outcomes: \[\Large \begin{gathered} a)HHH \hfill \\ b)HHT \hfill \\ c)HTH \hfill \\ d)HTT \hfill \\ e)THT \hfill \\ f)THH \hfill \\ g)TTT \hfill \\ h)TTH \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

Okay :}

OpenStudy (michele_laino):

now, we have to start from outcome a) and, with the same procedure we get these two new outcomes: \[\Large \begin{gathered} HHHH \hfill \\ HHHT \hfill \\ \end{gathered} \]

zarkam21 (zarkam21):

Yup :}

zarkam21 (zarkam21):

and then it would be HHTH and HHTT

OpenStudy (michele_laino):

starting from outcome b) I get these ones: \[\Large \begin{gathered} HHTH \hfill \\ HHTT \hfill \\ \end{gathered} \]

OpenStudy (michele_laino):

and we have to repeat the same procedure for the remaining outcomes c), d), e), f), g) and H)

OpenStudy (michele_laino):

so we get these outcomes: \[\Large \begin{gathered} 1)HHHH \hfill \\ 2)HHHT \hfill \\ 3)HHTH \hfill \\ 4)HHTT \hfill \\ 5)HTHH \hfill \\ 6)HTHT \hfill \\ 7)HTTT \hfill \\ 8)HTTH \hfill \\ 9)THTT \hfill \\ 10)THTH \hfill \\ 11)THHT \hfill \\ 12)THHH \hfill \\ 13)TTTT \hfill \\ 14)TTTH \hfill \\ 15)TTHT \hfill \\ 16)TTHH \hfill \\ \end{gathered} \]

OpenStudy (michele_laino):

that is the answer for part II

OpenStudy (michele_laino):

as you can see there are 16 possible outcomes, namely the number which we have computed in part I

zarkam21 (zarkam21):

Yes :}

OpenStudy (michele_laino):

now, for part III, we have highlight those outcomes which contains two T, namely TT

OpenStudy (michele_laino):

how many outcomes contain two (T)

zarkam21 (zarkam21):

2 or more or just two

OpenStudy (michele_laino):

I got six outcomes, precisely the subsequent outcomes: #4, #6, #8 ,#10, #11, #16

zarkam21 (zarkam21):

Okay :}

OpenStudy (michele_laino):

so the probability to have two flips which comes up with (T) is: p=favorable outcomes/possible outcomes=6/16 am I right?

zarkam21 (zarkam21):

Yes

zarkam21 (zarkam21):

But would't 6/16 be reduced

zarkam21 (zarkam21):

@Michele_Laino

OpenStudy (michele_laino):

it is: \[\Large p = \frac{6}{{16}} = \frac{3}{8}\]

zarkam21 (zarkam21):

for part II right?

OpenStudy (michele_laino):

for part III is right!

zarkam21 (zarkam21):

oh okay part III?

zarkam21 (zarkam21):

next is part IV

OpenStudy (michele_laino):

ok!

OpenStudy (michele_laino):

here we have to highlight those outcomes which contain three (H). How many outcomes do contain three (H) ?

zarkam21 (zarkam21):

Okay so #2, #3, #5, and #12

OpenStudy (michele_laino):

correct! we have 5 outcomes, so the requested probability, is: p=favorable outcomes/possible outcomes=\[\Large p = \frac{5}{{16}}\]

OpenStudy (michele_laino):

oops.. sorry we have 4 outcomes, so the requested probability is: \[\Large p = \frac{4}{{16}} = \frac{1}{4}\]

zarkam21 (zarkam21):

okay :}

zarkam21 (zarkam21):

Thank you sooo much !!!!!!!

OpenStudy (michele_laino):

:) :)

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