Circumference of circle problem

[MathsFormula]

Hello,
My answer to this apparently simple problem does not match the textbook answer. Please advise where I have gone wrong. Thank you.

A fly is perched on the tip of the minute hand of a clock. 14.4cm from he centre of the clock face.

How far does the fly move between 12 o’clock and 12:30?


My calculation: circumference = 2πr = 2π x 14.4 = 28.8π

So thedistance travelled between 12 and 12:30 is 28.8π / 2 = 45.2cm




My answer =45.2cm but the book says 22.6cm.

 

[jonah2.0]

DISCLAIMER: Beer soaked rambling/opinion/observation/reckoning ahead. Read at your own risk. Not to be taken seriously. In no event shall the wandering math knight-errant Sir jonah in his inebriated state be liable to anyone for special, collateral, incidental, or consequential damages in connection with or arising out of the use of his beer (and tequila) powered views.

Hello,
My answer to this apparently simple problem does not match the textbook answer. Please advise where I have gone wrong. Thank you.

A fly is perched on the tip of the minute hand of a clock. 14.4cm from he centre of the clock face.

How far does the fly move between 12 o’clock and 12:30?


My calculation: circumference = 2πr = 2π x 14.4 = 28.8π

So thedistance travelled between 12 and 12:30 is 28.8π / 2 = 45.2cm




My answer =45.2cm but the book says 22.6cm.

Your answer is correct.

 

[Ishuda]

Hello,
My answer to this apparently simple problem does not match the textbook answer. Please advise where I have gone wrong. Thank you.

A fly is perched on the tip of the minute hand of a clock. 14.4cm from he centre of the clock face.

How far does the fly move between 12 o’clock and 12:30?


My calculation: circumference = 2πr = 2π x 14.4 = 28.8π

So thedistance travelled between 12 and 12:30 is 28.8π / 2 = 45.2cm




My answer =45.2cm but the book says 22.6cm.

I generally don't like to disagree with Sir Jonah since, even in his beer soaked rambling/opinion/observation/reckoning, he is fairly astute. Nor do I like to disagree with official answers. However, in this case, my interpretation of the question means I must disagree with both. I have no problem with the 28.8\(\displaystyle \pi\) ~ 90.48 cm per revolution of the minute hand which would lead to a 90.48 cm net distance traveled between 12:00 (straight up) and 12:30 (straight up). However, I think one should note that there are 30 revolutions of the minute hand between 12:00 and 12:30 [assumed in the same hour] and that the question does not ask for the net distance, so an assumed total distance would be the proper answer.