Final answer:
To find the probability of passing all three tests at the first attempt, multiply the pass rates. To find the probability of passing all three tests in four attempts, consider the combinations of passes and failures.
Step-by-step explanation:
To find the probability that a candidate passes all three tests at the first attempt, you need to multiply the pass rates for each part. Let's assume the pass rates for the three parts are P1, P2, and P3, respectively. The overall probability can be calculated as P = P1 * P2 * P3. Since the question doesn't provide the specific pass rates, I can't give you the exact value, but it should be a product of three fractions.
To find the probability that a candidate passes all three tests in a total of exactly four attempts, we need to account for the possible combinations of test parts passed and failed in each attempt. We can use the binomial coefficient formula to calculate the number of ways to arrange the passes and failures. Let's assume the pass rates for the three parts are P1, P2, and P3, and the failure rates are Q1 = 1 - P1, Q2 = 1 - P2, and Q3 = 1 - P3. The probability can be calculated as:
P = (P1 * P2 * P3) * (Q1 * Q2 * Q3) * (Q1 * Q2 * P3) * (Q1 * P2 * Q3) * (P1 * Q2 * Q3)