Part A:
The probability that the birthday of three strangers were on Wednesday is given by
[tex]\left( \frac{1}{7} \right)^3= \bold{\frac{1}{343}} [/tex]
Part B:
The probability that the birthday of three strangers were on different days of the week is given by
[tex]\left( \frac{1}{7} \right)\left( \frac{1}{6} \right)\left( \frac{1}{5} \right)= \bold{\frac{1}{210}} [/tex]
Part C:
The probability that none of the three strangers were born on Saturday is given by
[tex]\left( \frac{6}{7} \right)^3= \bold{\frac{216}{343}}[/tex]