Question

Consider the random experiment of tossing 3 fair coins and observing how many of them come to rest with the heads side of the coin facing upwards. (Assume that each of the coins comes to rest with either its heads side or its tails side facing upwards (i.e., none of the coins comes to rest balanced on its edge).) Letting A denote the event that at least 1 of the coins comes to rest with its heads side upwards, B denote the event that none of the coins comes to rest with its heads side upwards, and S denote the sample space, which of the following statements does not include an abuse of notation?

a. S = 16
b. S = AUB
c. S - 4
d. S = 3
e. P(B) = φ

Answer 1

b. S = AUB

Explanation:

Since the coins are tossed 3 times and each coin has head, H and tail, T(2 sides), the sample space is S = 2 × 2 × 2 = 2³ = 8

All the possible outcomes are HTT, HHT, HHH, THH, TTH, HTH,THT and TTT

Since S denote the sample space

S = {HTT, HHT, HHH, THH, TTH, HTH,THT, TTT}

Since A denote the event that at least 1 of the coins comes to rest with its heads side upwards, the possible outcomes are HTT, HHT, HHH, THH, TTH, HTH and THT

So, A = {HTT, HHT, HHH, THH, TTH, HTH,THT}

Also B denote the event that none of the coins comes to rest with its heads side upwards, that is no heads. The possible outcome is TTT

So, B = {TTT}

Since S denote the sample space

S = {HTT, HHT, HHH, THH, TTH, HTH,THT, TTT}

So, A ∪ B = {HTT, HHT, HHH, THH, TTH, HTH,THT} ∪ {TTT} = {HTT, HHT, HHH, THH, TTH, HTH,THT, TTT} = S

So, S = A ∪ B

So, S = A ∪ B does not denote an abuse of notation.

The answer is b.