The answer is the option A, which is: A. Equilateral triangles.
The explanation for this answer is shown below:
By definition, a tetrahedron is a solid in three dimensions that has: six sides, four vertices and four triangular faces. These faces are equilateral triangles, which means that all the sides are equal and all the interior angles measure degrees.
The tetrahedron is also called "triangular pyramid".
Answer:
78.88%
Step-by-step explanation:
We have been given that
The z-score formula is given by
For
For
Now, we find the corresponding probability from the standard z score table.
For the z score -1.25, we have the probability 0.1056
For the z score 1.25, we have the probability 0.8944
Therefore, the percent of the trees that are between 20 and 30 years old is given by
0.8944 - 0.1056
= 0.7888
=78.88%