Final answer:
To calculate the probability of getting exactly four correct answers on a test where all answers were guessed, one would use the binomial probability formula. After computation with the specific values, it seems none of the provided options corresponds with the calculation, suggesting a potential error.
Step-by-step explanation:
The subject of this question is Mathematics, specifically dealing with probability and combinations.
To find the probability of getting exactly four correct answers on a 30-question multiple-choice test with five possible answers, we use the binomial probability formula. The formula is P(x) = (n choose x) * (p)^x * (1-p)^(n-x), where 'n choose x' represents the number of ways to choose x correct answers from n questions, 'p' is the probability of getting a question correct, and '1-p' is the probability of getting a question wrong.
For this particular problem, 'n' is 30 (the number of questions), 'x' is 4 (the number of correct answers), and 'p' is 1/5 (since there's only one correct answer out of five choices).
Thus, the formula looks like this: P(4) = (30 choose 4) * (1/5)^4 * (4/5)^(30-4)
Calculating this using a calculator or binomial theorem, we get P(4) = 27,405 * (1/625) * (4/5)^26.
Finally, after calculating the above expression, we find that the probability, rounded to four decimal places, is 0.1683. This is not one of the options provided, hence there might be a typo in the provided options or in the computation.