A coin is tossed 4 times Aat least 2 of the tosses are heads
A coin is tossed 4 times
A:at least 2 of the tosses are heads
B: The first and lst toss are the same
C: the second toss is tales and the third toss is heads
A.) P(A)
B.)P(B)
C.)P(AnB)
Solution
Sample space: (HHHH, HHHT, HHTH, HTHH, THHH, HHTT, HTHT, THTH, HTTH, THHT, TTHH, TTTH, TTHT, THTT, HTTT, TTTT) 16 events
A:at least 2 of the tosses are heads. These include: (HHHH, HHHT, HHTH, HTHH, THHH, HHTT, HTHT, THTH, HTTH, THHT, TTHH) 11 events
B: The first and last toss are the same. These include: (HHHH, HHTH, HTHH, HTTH, THHT, TTHT, THTT, TTTT) 8 events
C: the second toss is tales and the third toss is heads. These include: (HTHH, HTHT, TTHH, TTHT) 4 events
A.) P(A) = N(E)/N(S) = 11/16 or 0.6875
B.)P(B) = N(E)/N(S) = 8/16 or 0.5
C.)P(AnB)
The events included in both A and B are (HHHH, HHTH, HTHH, HTTH, THHT) 5 events
So the probability is N(E)/N(S) = 5/16 or 0.3125
