Final answer:
To find the mean of a group frequency distribution, the midpoint of each interval must be multiplied by the frequency and then summed up before dividing by the total number of data points. Without the actual data points or frequencies, the mean cannot be determined from the interval options provided.
Step-by-step explanation:
To calculate the mean of a distribution using group frequency distribution, you must first have the data points or a way to estimate the midpoint of each group interval.
For the intervals provided (20-29, 30-39, etc.), if we do not have the actual data points or frequencies, we cannot compute the mean directly from the intervals alone. Therefore, I cannot provide an answer from the choices a) 24.5, b) 35.5, c) 44.5, d) 30.5 without additional information.
However, if you have the frequencies for each interval, the mean can be calculated by finding the midpoint for each interval, multiplying each midpoint by the frequency for that interval, adding up those products, and then dividing by the total number of data points.