Question

1- A multiple choice test has 10 questions with 4 possible answers, one of which is correct. Among all possible results, how many will earn at least 70%?

2-How many 5-lists taken from[10]have no pair of adjacent elements equal? Howmany such lists have at least one pair of equal adjacent elements?

Answer 1

​​​​​​In multiple choice question probability getting correct answer (p) is 0.25 and getting wrong answer (q) is 0.75 how many get at least 70% means at least 7 questions should be correct hence here we use binomial distribution  

which mean out of 100 student approximately 4 students will score atleast 70 % marks