Question

Base diameter of conical helix is 50 mm, height of helix is 30 mm, angle between the base and slanting side of cone is 60 degrees. What is the top end diameter of the helix?

(a) 7.67 mm

(b) 15.3 mm

(c) 14.7 mm

(d) 6.7 mm

I got this question in an online interview.

This intriguing question originated from Helix upon a Cone in division Curves used in Engineering Practice of Engineering Drawing

Answer 1

The correct answer is (b) 15.3 mm

To explain I would say: Base radius = 25 mm. 30/tan (60) = difference between the base radius and top end radius = 17.3 mm. 25 mm- 17.3 mm = 7.67 mm (radius of top end radius). Diameter is 15.3 mm.