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

<h3>x = 21/5</h3>
Step-by-step explanation:
<h3>___________________________</h3>
<h3>Given →</h3>
5x:9 = 7:3
<h3>So,</h3>
→ 5x/9 = 7/3
→ x = (7 × 9)/(3 × 5)
→ x = 21/5
<h3>___________________________</h3>
<h3>Hope it helps you!!</h3>
The answer to the first question
is 2 1/4.
The answer to the second question is 8 sqroot 3. Hope I was able to help
Multiply both sides by 7. w=<span>105</span>