ใครเก่งความน่าจะเป็น ช่วยอธิบายข้อนี้หน่อยคะ

A student is taking a multiple choice test in which each question has four choices.Assuiming that he has no knowledge of the correct answer to any of the questions,he has decided on a strategy in which he will place four balls (marked A,B,C,D)into a box.He randomly selescts one ball for each question and replaces the ball in the box.The marking on the ball will determine his answer to the question.There are ten questions on the test.What is the probability that he will get

a)no more than one question correct?

Binomial Distribution ka Thank you ka