Final answer:
To find the percentile corresponding to x=15, use the Z-score formula.
Step-by-step explanation:
To find the percentile corresponding to x=15, we can use the Z-score formula: Z = (x - mean) / standard deviation. Plugging in the values given, we have Z = (15 - 12) / 2.6 = 1.15. Using a standard normal distribution table or a calculator, we can find that the area to the left of Z = 1.15 is approximately 0.8749. This corresponds to a percentile of 87.49%.
The correct answer is: a. 88th