What fraction of 0.8 is the sum of 0.4 and 0.3,

What fraction of 0.8 is the sum of 0.4 and 0.3,

(0.4 + 0.3) △ 0.8 = 7 / 8 = 7 / 8

If the radius of the bottom of a cone is increased to four times of the original, the height is reduced to several parts of the original, and the volume remains unchanged
emergency

4 times 4 equals 16, 1 divided by 16 equals 1 / 16

The height of a cylinder is equal to that of a cone. The bottom radius of the cylinder is 1 / 4 of the bottom radius of the cone. The volume of the cylinder is equivalent to several parts of the volume of the cone
Sorry, there's not enough money. I'll give it next time!

The volume of the column is the bottom area times the height = 3.14 * (1 / 4 * r) * (1 / 4 * r) * H
The volume of the cone is 1 / 3 of the bottom area times the height = (1 / 3) * 3.14 * r * r * H
［3.14＊（1／4＊R）＊（1／4＊R）＊H］／［（1／3）＊3.14＊R＊R＊H］
＝（1／16）／（1／3）
＝3／16
A: the volume of a cylinder is equivalent to 3 / 16 of that of a cone