Answer:
62.5%
Step-by-step explanation:
K +1 < or = -2
At means less than or equal to. It cannot be more than -2
The answer is 2500 milligrams
The probability is 0.0008.
I used a binomial probability on this one, since there are two outcomes (either pass or fail); the events are independent (the probability of one person passing does not influence the probability of another passing); and there are a fixed number of trials (in this case, 20).
For binomial probabilities, we use the formula:

With our information, we have: