单选题Blaire, Chad, Erin, and Jordan randomly arranged in four seats at the front row of the classroom. What is the probability that Chad and Blaire are sitting next to each other?A0. 15B0. 25C0. 35D0. 4E0. 5
单选题
Blaire, Chad, Erin, and Jordan randomly arranged in four seats at the front row of the classroom. What is the probability that Chad and Blaire are sitting next to each other?
A
0. 15
B
0. 25
C
0. 35
D
0. 4
E
0. 5
参考解析
解析:
There are a total of 4 × 3 × 2 × 1 = 24 ways to arrange four people. Let B = Blaire, C = Chad, E = Erin, and J = Jordan. The different arrangements where Chad is next to Blaire are:
BCEJ, BCJE, CBEJ, CBJE, JBCE, EBCJ, JCBE, ECBJ, EJBC, JEBC, EJCB, and JECB.
There are 12 ways for Chad to be seated next to Blaire. P (Chad next to Blaire) =12/24 = 0. 5
There are a total of 4 × 3 × 2 × 1 = 24 ways to arrange four people. Let B = Blaire, C = Chad, E = Erin, and J = Jordan. The different arrangements where Chad is next to Blaire are:
BCEJ, BCJE, CBEJ, CBJE, JBCE, EBCJ, JCBE, ECBJ, EJBC, JEBC, EJCB, and JECB.
There are 12 ways for Chad to be seated next to Blaire. P (Chad next to Blaire) =12/24 = 0. 5
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