Dates of birth of some persons are given below. Find out the date of birth of the oldest person: A. 12.08.1989 B. 13.09.1991 C. 19.06.1991 D. 20.02.1989 E. 22.03.1991 F. 20.01.1991
D
Finding the Oldest Person by Date of Birth
The question asks us to identify the oldest person among a list of individuals, given their dates of birth. To find the oldest person, we need to find the earliest date of birth among the ones provided. A person born on an earlier date is older than a person born on a later date.
Dates of Birth Provided
Here are the dates of birth for the persons:
- A: 12.08.1989
- B: 13.09.1991
- C: 19.06.1991
- D: 20.02.1989
- E: 22.03.1991
- F: 20.01.1991
- G: 20.12.1989
Comparing Dates to Find the Oldest Person
To find the earliest date, we compare the dates chronologically:
- Compare the Year: The earliest year indicates an older person. The years provided are 1989 and 1991. The year 1989 is earlier than 1991. Therefore, the oldest person must have been born in 1989.
- Filter Dates by Earliest Year: The dates of birth in 1989 are:
- A: 12.08.1989
- D: 20.02.1989
- G: 20.12.1989
- Compare the Month (for dates in the earliest year): For the dates in 1989, we compare the months. The months are 08 (August), 02 (February), and 12 (December). February (02) is the earliest month among these.
- Identify the Earliest Date in the Earliest Year: The date with the earliest month (February) in 1989 is 20.02.1989 (Person D). Even though other dates in 1989 exist (August and December), February is the earliest month. If there were multiple people born in February 1989, we would then compare the day. However, in this case, only one person (D) was born in February 1989 among the 1989 dates.
Based on this comparison, the date 20.02.1989 is the earliest date of birth among all the given dates.
Identifying the Oldest Person
The date 20.02.1989 corresponds to Person D.
Therefore, Person D is the oldest person.
Summary of Dates and Corresponding Persons
| Person | Date of Birth | Year | Month | Day |
|---|---|---|---|---|
| A | 12.08.1989 | 1989 | 08 | 12 |
| B | 13.09.1991 | 1991 | 09 | 13 |
| C | 19.06.1991 | 1991 | 06 | 19 |
| D | 20.02.1989 | 1989 | 02 | 20 |
| E | 22.03.1991 | 1991 | 03 | 22 |
| F | 20.01.1991 | 1991 | 01 | 20 |
| G | 20.12.1989 | 1989 | 12 | 20 |
Comparing the years, 1989 is the earliest. Within 1989, the months are 08, 02, 12. The earliest month is 02. The person born on 20.02.1989 is D.
Revision Table: Finding Oldest Person
| Step | Action | Outcome for this problem |
|---|---|---|
| 1 | List all dates of birth. | 7 dates provided (A-G). |
| 2 | Compare years. Identify earliest year(s). | 1989 is earlier than 1991. Focus on 1989 dates. |
| 3 | If multiple dates have the earliest year, compare months for those dates. Identify earliest month(s). | Months in 1989: 08, 02, 12. Earliest month is 02 (February). |
| 4 | If multiple dates have the earliest year and month, compare days for those dates. Identify earliest day. | Only one date in Feb 1989: 20.02.1989. No need to compare days further for this case. |
| 5 | The date identified in the last step is the earliest date of birth. The corresponding person is the oldest. | Earliest date is 20.02.1989. Corresponds to Person D. |
Additional Information: Date Comparison Logic
Understanding how to compare dates is fundamental in various reasoning problems. Dates are typically compared hierarchically: Year, then Month, then Day. This is similar to how we compare numbers from left to right (most significant digit first).
- A date in an earlier year is always earlier than a date in a later year, regardless of month or day. (e.g., 31.12.1990 is earlier than 01.01.1991).
- If the years are the same, the date with the earlier month is earlier. (e.g., 15.03.2000 is earlier than 15.04.2000).
- If the years and months are the same, the date with the earlier day is earlier. (e.g., 10.07.2020 is earlier than 20.07.2020).
This structured comparison allows us to efficiently determine the chronological order of events or the age of individuals based on their birth dates.
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