All answers are correct 
Keep it up
        
                    
             
        
        
        
Answer:
The probability is 
Step-by-step explanation:
If she has n distinct password candidates and only one of which will successfully log her into a secure system, the probability that her first first successful login will be on her k-th try is:
If k=1

Because, in her first try she has n possibles options and just one give her a successful login.
If k=2

Because, in her first try she has n possibles options and n-1 that are not correct, then, she has n-1 possibles options and 1 of that give her a successful login.
If k=3

Because, in her first try she has n possibles options and n-1 that are not correct, then, she has n-1 possibles options and n-2 that are not correct and after that, she has n-2 possibles options and 1 give her a successful login.
Finally, no matter what is the value of k, the probability that her first successful login will be (exactly) on her k-th try is 1/n
 
        
             
        
        
        
The distance between the two endpoints is :
14.212 or about 14.21 ( rounded to the nearest hundredth)
        
                    
             
        
        
        
Answer:
it's 5 because 20 -15 is 5