SOLUTION: In the diagram, point N is on the inside of the cylinder, 10 cm from the bottom, and point M is on the outside of the cylinder, diametrically opposite Point N, 4 cm from the bottom

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Question 1171270: In the diagram, point N is on the inside of the cylinder, 10 cm from the bottom, and point M is on the outside of the cylinder, diametrically opposite Point N, 4 cm from the bottom. An ant walks from point M to point N, using the shortest possible route. The cylinder has height 12 cm and circumference 15 cm. When the ant got to the top of the cylinder, how many cm did it still have to walk? Ignore the thickness of the cylinder wall.
A) 3
B) 2
C) 2.25
D) 2.5
E) 2.75
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Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

To get from point M (on the outside of cylinder) to point N+(on the inside of cylinder), ant must go up 12-4+=+8cm, then it must go down+12-10+=+2cm.
So the ant must move vertically 8%2B2+=+10cm+and horizontally 15%2F2+=+7.5cm
x = length of shortest path from point M+to point N
x%5E2+=+%2810cm%29%5E2+%2B+%287.5cm%29%5E2+=+156.25cm%5E2
x+=+12.5cm
Once it reaches top, it has already travelled 8%2F%288%2B2%29+=+4%2F5 of total distance.
So it has just 1%2F5 of distance left to get to N
= 12.5cm%2F5
= 2.5cm


answer: D) 2.5