Scientists have estimated that if 100 people answer there question, the sample size is large enough for there research.

[answerhappygod]

Scientists have estimated that if 100 people answer there
question, the sample size is large enough for there research.
According to past experience it is known that only 70
percent who get the question will answer it.This is why
the scientists have sent the question for 150 people.The scientists
presume that the people will answer or not answer the question
independently of others. (a) Calculate by using the binomial
distribution (without normal approximation)the probability that the
scientists will get exactly x amount of answers to there
question, with the x values of 100, 101 and 130. (b)
Determine the probability using normal approximation that the
scientists get at least a 100 answers to there question.