我想问这道题为什么会选B！！！

dt815

When tossed, a certain coin has equal probability of landing on either side.  If the coin is tossed 3 times, what is the probability that it will land on the same side each time?

A. 1/8
B. 1/4    
C. 1/3    
D. 3/8    
E. 1/2



还有这道为什么会选A 我排列组合超级烂
Q7:
A company has assigned a distinct 3-digit code number to each of its 330 employees.  Each code number was formed from the digits 2, 3, 4, 5, 6, 7, 8, 9 and no digit appears more than once in any one code number.  How many unassigned code numbers are there?

A.    6
B.    58
C.    174
D.    182
E.    399
    
谢谢各位了~~

tomatoshirt

1) HHH HHT HTT HTH TTT THT THH TTH = 一共８个outcome. 2/8 = 1/4

2) 8x7x6 = 336 (个选择）- 330　(员工） = 6

dt815

原来是这样~谢谢~