Could you please give me the most simplest/easiest solution step by step for the below questions? I have seen the recording 2-3 times for GRE MINI EXAM 23. But I haven’t understood a single thing for these questions. Kindly help.

Share your approach for each problem.

For 1,2,4 question I tried again today and I got the solution. But for 3 question I tried to divide 0.01 by 0.01/100 = .0001 I got, after that I’m not getting what to do?

What do you think we need to equate to 0.0001?

I’m stuck after this, I was thinking to use Combinations formula. Please give me solution.

Suppose there are n characters in the keypad. What is the probability one correctly guesses the password?

(You may want to try with an easier example, say 2 or 3 characters)