Answer:


<em>Hope this helps and have a great day!!!</em>
<em>
</em>
Give me 8 mins i will answer in the comments
Answer:
3/4
Step-by-step explanation:
A ratio of the diameters is one diameter divided by the other so the miniDVD divided by the DVD = 9/12 or 3/4.
1. Mean.

2. <span>Standard deviation.
First we have to square each value and calculate the mean of that squares:

so the variance:

and the standard deviation:

</span>