Stat word problem

Question

A scientist conducted a hybridization experiment using peas with green pods and yellow pods. He crossed peas in such a way that 25% (or 139) of the 556 offspring peas were expected to have yellow pods. Instead of getting 139 peas with yellow pods, he obtained 143. Assume that the rate of 25% is correct.
a. Find the probability that among the 556 offspring peas, exactly 143 have yellow pods.
b. Find the probability that among the 556 offspring peas, at least 143 have yellow pods.
c. Which result is useful for determining whether the claimed rate of 25% is incorrect? (Part (a) or part (b)?)
d. Is there strong evidence to suggest that the rate of 25% is incorrect?

Answer 1

P( x=139)= 139/556= 0.25

 

p(x>139) = 1- p(139)= 1-0.25

= 0.75