Answer:
1.8 in.
Explanation:
Hi there!
1) Determine the radius of the base
where r is the radius of the base and h is the height of the cone
Plug in the known values (h=4.2, V=3.6)

Isolate r; divide both sides by 4.2

Multiply both sides by 3

Divide both sides by π

Take the square root of both sides

2) Determine the diameter
Now that we have the radius, to find the diameter, multiply r by 2:

Therefore, the diameter is 1.8 in. when rounded to the nearest tenth.
I hope this helps!