The height is 5×3= 15 decimeter.

Volume = 5 * 5 * 3.14 *15 =1177.5 cubic decimeter.

Bottom circumference =94.2÷3=3 1.4

The radius is 3 1.4÷3. 14÷2=5.

The volume is reduced by 5*5*3. 14*3=235.5 cubic centimeters.

Radius = 3 14 ÷ 3. 14 ÷ 2 = 50m.

Covering an area of 50*50*3. 14=7850 square meters.

Two cars, A and B, set off from two places 306 kilometers apart at the same time, headed for each other and met after 4.5 hours. -The sum of speeds per hour =306÷4.5=68.

A car speed = 68 * 8/ 17 = 32km/h, and B car speed = 68-32 = 36km/h.

Sum of length, width and height = 12 ÷ 4 = 3m = 30m.

Length =30*3/6= 15dm, width =30*2/6= 10dm and height =5dm.

Volume = 15× 10×5=750 cubic decimeter.