Probability of typographical errors per page

Question

Answer 1

b) 50% chance of getting less than 5

P(<5) =about 0.50 or slightly less than 0.50

P(less than 5) = 0.50 minus the (1/2)Pr(exactly 5)

if the distribution is normal.

if it's skewed, the probability is different

if there were 99 pages each with 4 errors and one page with 104 errors, the mean errors per page is (4(99)+104)/100 = exactly 5. Then the Pr(<5) = 99%, Pr(=5) = 0%= Pr(exactly zero errors) = 0%