A brother and a sister are in the same math class. There are 9 boys and 12 girls in the class. One boy and one girl are randomly chosen. What is the probability that both the brother and the sister are chosen?

9 : 12 or 9 to 12

Step-by-step explanation:

Given:
height = 1.8
length = 2.4
width = 1.2

The solid figure that the stairs can be broken into is RECTANGULAR PRISM.
Its dimension would be 2.4 by 1.2 by 1.8

We need to get the volume of 1 solid rectangular prism.
Volume = length * width * height
V = 2.4 * 1.2 * 1.8
V = 5.184 cubic units

Let us assume that the unit measure used is feet.
It is said that the weight of concrete is approximately 150 pounds per cubic foot.
To get the total weight of the concrete, multiply volume by 150 pounds per cubic foot.

5.184 cubic feet * 150 pounds/cubic ft = 5.184  * 150 pounds = 777.60 pounds