In simpler terms, this question is asking, "arrange this group in order of increasing age, then identify the top 25% of eldest members of the group".
The ages need to be tallied, with each instance of each number counted separately. Once tallied, we can calculate an average age for the group, which will assist in giving perspective to the results (since a heavy bias toward young or old ages will skew the results and cause the top 75% of ages to grow or shrink disproportionately).
The ages tally as follows:
There are 60 individuals with ages ranging from 29 to 66. The average age is 49. The median age is 48.
There is a difficulty in identifying the 75th percentile of members by age; the 45th member of the group is part of a group of six members that are all 56 years old, so technically we have to count 56 among the top 25% despite not having more details about the exact ages of these members.
The 75th percentile begins with the three older members of the group of 56, and includes the following;
2 57 year olds
To answer the question in another perspective, the oldest 25% of ages between 29 and 66 is anyone over the age of 56.75 years, which coincides with the results above. In order to definitively answer this question, more information is needed on the group of 56 year olds.