A letter is chosen at random from the word "STATISTICS".
a. (i) Find the probability of selecting the letter "S".
b. (ii) Find the probability of selecting a consonant.
c. (iii) Consider the event G: "selecting a letter from the word \"STATISTICS\"". State whether G is certain, impossible, or neither, and give its probability.
d. (iv) Using your answers to parts (i) and (ii), verify that the sum of the probabilities of the events "selecting a vowel" and "selecting a consonant" equals 1.