Explanation
To find the probability of earning a return in excess of 20% for each mutual fund, we need to calculate the z-score for each fund and use the z-table to find the corresponding probability.
Z-Score Formula:
Z=Standard DeviationDesired Return−Mean Return
Calculations:
Fund X:
- Mean = 25%, Std. Dev. = 2%
- Z=2%20%−25%=2%−5%=−2.5
- P(Z < -2.5) ≈ 0.0062 (from z-table)
- P(X > 20%) = 1 - P(Z < -2.5) = 1 - 0.0062 = 0.9938 = 99.38%
Fund Y:
- Mean = 24.8%, Std. Dev. = 3%
- Z=3%20%−24.8%=3%−4.8%=−1.6
- P(Z < -1.6) ≈ 0.0548 (from z-table)
- P(Y > 20%) = 1 - P(Z < -1.6) = 1 - 0.0548 = 0.9452 = 94.52%
Fund Z:
- Mean = 26%, Std. Dev. = 4%
- Z=4%20%−26%=4%−6%=−1.5
- P(Z < -1.5) ≈ 0.0668 (from z-table)
- P(Z > 20%) = 1 - P(Z < -1.5) = 1 - 0.0668 = 0.9332 = 93.32%
Analysis of Options:
- Option A (1.60% for Fund Y) - Incorrect, this is approximately P(Z < -1.6) not P(Y > 20%)
- Option B (94.52% for Fund Z) - Incorrect, this is actually the probability for Fund Y
- Option C (99.38% for Fund X) - CORRECT - Matches our calculation for Fund X
- Option D (11.6% for Fund Y) - Incorrect, this doesn't match any of our calculated probabilities
Therefore, the correct answer is C - 99.38% for Fund X.