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Q6768/80Q69
Q68·CSAT · Prelims 2022

Determining exact clock overlap times using relative angular speed

ReasoningClocksStatement-basedHard

Question

Consider the following statements:

1Between 3:16 p.m. and 3:17 p.m., both hour hand and minute hand coincide.
2Between 4:58 p.m. and 4:59 p.m., both minute hand and second hand coincide.

Which of the above statements is/are correct?

Options

a

1 only

b

2 only

c

Both 1 and 2

Answer
d

Neither 1 nor 2

Explanation

Statement 1: The hour and minute hands coincide when the angle between them is 0^\circ. Using the formula θ = 30H - 5.5M = 0: 30(3) = 5.5M \implies 90 = 5.5M \implies M = 90/5.5 = 180/11 = 16.36 minutes. Since 16.36 minutes falls exactly between the 16th and 17th minute marks, Statement 1 is correct.

Statement 2: The minute hand and the second hand. The second hand completes a full 360^\circ sweep of the entire clock face during every single 1-minute interval. Consequently, it is physically guaranteed to pass over the slow-moving minute hand exactly once during any given minute (excluding perfect overlaps at the exact 60s boundary). Between 4:58 and 4:59, the minute hand sits near the 58-minute mark. As the second hand sweeps through its 60-second cycle, it will inevitably overtake the minute hand around the 58th second. Statement 2 is geometrically irrefutable.

Fast-moving dial indicators (like the second hand) are mathematically guaranteed to sweep past slower hands exactly once during their cycle period, guaranteeing overlap events inside defined minute windows.

Answer: (c).

Question details

Year

2022

Paper

CSAT

Question

Q68

Section

Logical & Analytical Reasoning

Sub-topic

Clocks

Type

Statement-based

Difficulty

Hard

Source hint

Hands coincide between 3:16 and 3:17

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