It is 6:00 pm, when can Deepak get next bus from Noida to Delhi? I. Buses for…

Concept:

In a Data Sufficiency question, a statement is sufficient only if it lets you compute one definite value for what is asked. Check each statement alone first; only combine them if neither alone gives a definite answer.

Application:

• Statement I: gives the bus frequency (every 30 minutes, until 11 pm) but no reference departure time, so the exact clock time of the next bus cannot be fixed. Alone, it is not sufficient.

• Statement II: gives a reference departure time (a bus left 20 minutes before 6:00 pm, i.e. at 5:40 pm) but no frequency, so the time of the following bus cannot be fixed. Alone, it is not sufficient.

Combining Statement I and Statement II:

1. From Statement II, a bus left Noida for Delhi at 5:40 pm (20 minutes before 6:00 pm).

2. From Statement I, buses run every 30 minutes, so the next bus after 5:40 pm departs 30 minutes later.

3. 5:40 pm + 30 minutes = 6:10 pm, so Deepak can get the next bus at 6:10 pm.

Cross-check:

Neither statement alone could produce this result: Statement I alone has no anchor time to add the interval to, and Statement II alone has no interval to add to the anchor time. Only using both statements together fixes a single definite departure time, confirming both are needed.

Answer: Both I and II are needed.