Calendars — On which date is Amit's birthday in September 2010? Statements: I. In September 2009, his birthday fell on the last Thursday of the month. II. In September 2010, his birthday will fall on the last Friday of the month.
Verbal Reasoning
Data Sufficiency
Difficulty: Medium
Choose an option
Answer
Correct Answer: Statement II alone is sufficient; Statement I alone is not sufficient.
Explanation
Introduction / Context:We need the exact date (calendar date number) of Amit's September 2010 birthday using weekday placement information.
Given Data / Assumptions:
- II provides that in Sep 2010 the birthday is on the last Friday.
- Month/year are fixed (September 2010 has 30 days).
- I references Sep 2009, which is not required if II already pins the weekday position within Sep 2010.
Concept / Approach:For a fixed month/year, the phrase 'last Friday' corresponds to a unique date.
Step-by-Step Solution:
Determine the dates for Fridays in September 2010 and select the largest one within 1–30. (This yields a unique date number.)Statement I is historical and does not alter September 2010’s weekday alignment for identifying the last Friday.Verification / Alternative check:Calendar enumeration confirms a single 'last Friday' date exists for any specified month/year.
Why Other Options Are Wrong:
- A/C/E/D: II alone suffices; I is superfluous.
Common Pitfalls:Thinking the previous year's weekday is required; it is not when the target month/year is explicit.
Final Answer:B — Statement II alone suffices (unique 'last Friday' date in Sep 2010).