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Question -

A fair coin is tossed four times, and a person win Rs 1 for each head and lose Rs 1.50 for each tail that turns up.
From the sample space calculate how many different amounts of money you can have after four tosses and the probability of having each of these amounts.



Answer -

Since either coin can turn up Head (H) or Tail (T), are thepossible outcomes.

But, now coin is tossed four times so the possible samplespace contains,

S = (HHHH, HHHT, HHTH, HTHH, THHH, HHTT, HTHT, THHT, HTTH,THTH, TTHH,

TTTH, TTHT, THTT, HTTT, TTTT)

As per the condition given the question, a person will winor lose money depending up on the face of the coin so,

(i) For 4 heads = 1 + 1 + 1 + 1 = тВ╣ 4

So, he wins тВ╣ 4

(ii) For 3 heads and 1 tail = 1 + 1 + 1 тАУ 1.50

= 3 тАУ 1.50

= тВ╣ 1.50

So, he will be winning тВ╣ 1.50

(iii) For 2 heads and 2 tails = 1 + 1 тАУ 1.50 тАУ 1.50

= 2 тАУ 3

= тАУ тВ╣ 1

So, he will be losing тВ╣ 1

(iv)For 1 head and 3 tails = 1 тАУ 1.50 тАУ 1.50 тАУ 1.50

= 1 тАУ 4.50

= тАУ тВ╣ 3.50

So, he will be losing Rs. 3.50

(v) For 4 tails = тАУ 1.50 тАУ 1.50 тАУ 1.50 тАУ 1.50

= тАУ тВ╣ 6

So, he will be losing Rs. 6

Now the sample space of amounts is

S= {4, 1.50, 1.50, 1.50, 1.50, тАУ 1, тАУ 1, тАУ 1, тАУ 1, тАУ 1, тАУ 1,тАУ 3.50, тАУ 3.50, тАУ 3.50, тАУ 3.50, тАУ 6}

Then, n (S) = 16

P (winning тВ╣ 4) = 1/16

P (winning тВ╣ 1.50) = 4/16 тАж [divide both numerator anddenominator by 4]

= ┬╝

P (winning тВ╣ 1) = 6/16 тАж [divide both numerator anddenominator by 2]

= 3/8

P (winning тВ╣ 3.50) = 4/16 тАж [divide both numerator anddenominator by 4]

= ┬╝

P (winning тВ╣ 6) = 1/16

= 3/8

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