Question

One digit of the decimal representation of 5/7 is randomly selected. what is the probability that the digit is a 4? express your answer as a common fraction.

Answer 1

Explanation:

5/7 = 0.714285714285714285714...

what we see is that there is a group of 6 digits that keeps repeating in all eternity :

714285

4 is exactly one digit out of the 6.

so, bottom line, 1/6 of all the digits are 4s.

therefore, the probability to select a 4 is 1/6.