Final answer:
To find the probability that a male passenger can fit through the doorway without bending, we need to calculate the z-score and look it up in the standard normal distribution table. To find the probability that the mean height of 75 men is less than 78 inches, we need to calculate the standard error of the mean and use the t-distribution. Comparing the probabilities will determine which result is more relevant.
Step-by-step explanation:
To find the probability that a male passenger can fit through the doorway without bending (part a), we need to determine the proportion of men who are shorter than the doorway height. We are given that the mean height of the male population is 69 inches with a standard deviation of 2.8 inches. We can use the standard normal distribution to calculate the probability.
- Calculate the z-score using the formula: z = (x - mean) / standard deviation, where x is the doorway height.
- Look up the z-score in the standard normal distribution table to find the corresponding probability.
- Round the probability to four decimal places.
To find the probability that the mean height of the 75 men is less than 78 inches (part b), we need to calculate the standard error of the mean and use the t-distribution. Then, we can look up the probability in the t-distribution table. We can also compare the probabilities from parts (a) and (b) to determine which is more relevant for considering comfort and safety of passengers.