When Julia is writing a first draft, there is 0.7 probability that there will be no spelling mistakes on a page

When Julia is writing a first draft, there is 0.7 probability that there will be no spelling mistakes on a page. One day, Julia writes a first draft that is 4 pages long. Assuming that Julia is equally likely to have a spelling mistake on each of the 4 pages, what is the probability that she will have no spelling mistakes on at least one of them? Round your answer to the nearest hundredth. P(at least one without mistakes)=

Assume P(E) = getting mistakes on all 4 pages.

Recall that the probability of an event not happening = 1 - P(E).

So,

P(at least one without mistakes) =1 − P(mistakes on all 4)

= 1 - `(0.3)^4` = 1−`(0.3)^4`

= 1 − 0.0081

= 0.9919

P(at least one without mistakes) ≈ 0.99.