According to the circumference of a circle =2πr, the ratio of circumference is equal to the ratio of radius.

If the radius of cylinder bottom is 3r, the radius of cone bottom is 2r, the height of cylinder is h, and the height of cone is h.

V-pillar =π(3r)? H=9πr？ H

V-cone =( 1/3)π(2r)? h=(4/3)πr？ h

V-pillar /V-cone =(9πr? H)/[(4/3)πr？ h]=27H/4h=9/8

∴H/h= 1/6

Choose answer B.

The above is the conventional calculation method.

But in the exam, we should not only master the basic knowledge and calculation ability, but also consider that the exam is time-limited. In order to save time, some topics have shortcuts.

For multiple-choice questions that have been answered, sometimes it is a test of your flexible application of basic knowledge.

Like you, you can also use the basic knowledge flexibly to guess the answer (of course, it is not a blind guess, but an educated guess).

The volume ratio of a cone and a cylinder with the same bottom radius and height is 1:3.

That is to say, the volume of a cone is much smaller than that of a cylinder when the radius and height of the bottom surface are equal.

In the title, the bottom radius of the cone is smaller than the bottom radius of the cylinder (3:2), but the two volumes are similar (9:8). Therefore, the height of the cone is much greater than that of the cylinder. Look at the four answers again, only item B meets this condition, so choose B.

In this way, you can get more time to do the following questions without complicated calculation process!

However, not all multiple-choice questions can do this, only a few other questions can. This is to test your flexibility. Don't try to find shortcuts for every topic just to be lazy, it will waste time!