Answer:
z=-1.591
Step-by-step explanation:
Null Hypotheses,

So we use z-test for one population proportion (right-tailed test)
According to this informaton, we defined that

(critical value)
So our Rejection region is 

Not rejection.
Answer:
Average speed is 3 kilometers an hour
She is using 1/3 of vegatable oil and 1/4 of vinegar.
I think the answer is 3 and two thirds yards