A Circular Clock has a Minute Hand Measuring 12 Inches Long GMAT Problem Solving

Question: A circular clock has a minute hand measuring 12 inches long. How far, in inches, does the outermost tip of the minute hand travel in 20 minutes?

  1. 12π
  2. 24π

Correct Answer: C
Solution and Explanation:
Approach Solution 1:

Given:

A circular clock has a minute hand measuring 12 inches long

To find:
How far, in inches, does the outermost tip of the minute hand travel in 20 minutes

Approach and Working:
In 1 hour or 60 minutes time, the minute hand makes one whole revolution, completing a distance equivalent to the circumference of the circle

  • If the radius of the circle is 12 inches long, the circumference = 2 * π * 12 = 24π

Now, 24π distance is covered in 60 minutes

  • Therefore, in 20 minutes, the distance the minute hand will cover = 20/60 * 24π = 8π

Approach Solution 2:

In 60 minutes, the outermost tip of the minute hand travels one revolution around the centre of the clock, i.e., the circumference of a circle with radius 12 inches. Thus, in 60 minutes, the outermost tip of the minute hand travels 2 x π x 12 = 24π inches. Since 20 minutes is 1/3 of 60 minutes, the outermost tip of the minute hand travels 24π x 1/3 = 8π inches.

Approach Solution 3:
In one minute there is a change of 6 degrees.
20 min = 120 degrees change
So theta/360*2*π*radius should be the answer = 120/360*2*π*12= 8*π

“A circular clock has a minute hand measuring 12 inches long. How far”- is a topic of the GMAT Quantitative reasoning section of GMAT. To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. GMAT Quant practice papers improve the mathematical knowledge of the candidates as it represents multiple sorts of quantitative problems.

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