These values have mean of 17 and standard deviation of about 4.1. If instead we first calculate the range of our data as 25 â 12 = 13, and then divide this number by four we have our estimate of the standard deviation as 13/4 = 3.25.
Thermoset plastics are types of plastics that retain the shapes that they are molded into. In other words, these are hard plastics. They are very durable and most of the time can be used and reused many times. These are the types of plastics that are used in aircraft parts, tires, and many others. The other half of the main types of plastics is thermoplastic.
Number 2. Number 2 plastics are made out of high-density polyethylene (HDPE) and are very versatile. These plastics are stiff and have good barrier properties. They are useful in the packaging of short shelf-life products like milk, and hard plastic products such as those used in plumbing.