alex has to take a quiz , which has 10 true false - type question each carry 1 mark . what is the probability that alex ' s can score more than 8 mark in the quiz . given that he decides to guess randomly on the quiz .  Select the correct option:
A) 12 / 1024
B) 11 / 1024
C) 11 / 256
D) 12 / 256
E) 14 / 256

Rationale: each question has 2 options ( true or false ) . total number of ways of answering all 10 questions = ( 2 ) 10 ( 2 ) 10 more than 8 correct means either 9 correct or all correct . number of ways such that 9 correct = 10 ! / 9 ! = 10 number of ways of all correct = 1 therefore , probability of more than 8 correct = 11 / ( 2 ) 1011 / ( 2 ) 10 = 11 / 1024 answer : b
Answer: B