A three-digit personal identification number is chosen using the digits 1-9. The digits cannot be repeated. What is the approximate probability that the first digit will be 6?

How to do this , and can some one explain

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Consider the first four terms of the sequence below. what is the 8th term of this sequence?