In an average mass, each entry has equal weight. In a weighted average, we multiply each entry by a number representing its relative importance.
Assume that your class consists of 15 girls and 5 boys. Each girl has a mass of 54 kg, and each boy has a mass of 62 kg.
<em>Average mass</em> = (girl + boy)/2 = (54 kg + 62 kg)/2 = <em>58 kg</em>
<em>Weighted average (Method 1)
</em>
Use the <em>numbers of each</em> gender (15 girls + 5 boys)
,
Weighted average = (15×54 kg + 5×62 kg)/20 = (810 kg + 310 kg)/20
= 1120 kg/20 = <em>56 kg</em>.
If you put all the students on one giant balance, their total mass would be
1120 kg and the average mass of a student would be <em>56 kg.
</em>
<em>Weighted average (Method 2)
</em>
Use the <em>relative percentages</em> of each gender (75 % girls and 25 % boys).
Weighted average = 0.75×54 kg + 0.25×62 kg = 40.5 kg + 15.5 kg = <em>56 kg</em>
Each girl contributes 40.5 kg and each boy contributes 15.5 kg to the <em>weighted average</em> mass of a student.
The given question is incomplete. the complete question is:
The electron arrangement ions 
and 
are 2, 8, and 2, 8, 8 respectively.
Write the electronic arrangement of the elements X and Y.
Write the formula of the compound that would be formed between X and Y.
Answer: 1. The electronic arrangement for X and Y are 2,8, 3 and 2,8,5 respectively.
The formula of the compound formed is 
Explanation:
Electronic configuration is the arangement of electrons in an atom in order of increasing energies.
Cations are formed when electrons are lost by atoms and anions are formed when electrons are gained by atoms.
For formation of a neutral ionic compound, the charges on cation and anion must be balanced.
Here element X is having an oxidation state of +3 called as cation and is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral
Mezoic era began 252m years ago and ended 6.6m years ago.
It was a time of geological and biological transition. During this era the continents began to drift to their present configuration.
3 of the largest mass extinction occurred at this era. One which include the dinosaurs.
I hope this helped. :)
The correct answer is - D. Savannah is more humid and has higher precipitation than San Diego.
Despite both Savannah and San Diego being on the coast of an ocean, they do have differences in the climate. Savannah comes out on the Atlantic coast, while San Diego comes out on the Pacific Coast. Savannah is influenced by warm and wet air masses all year round, while San Diego is predominantly influenced by dry air masses because of the colder ocean currents. Savannah has a relatively stable temperature throughout the year, and it also has solid amount of precipitation, with the humidity in the air being always high. San Diego, on the other side, is hot for most of the year during the days, but the nights are relatively cool. There's very little precipitation, and the humidity in the air is not as high as in Savannah.
