The magnitude of a vector is the length of the vector. It is also known as the modulus of the vector. For any vector of the form <a,b>, the length is equal to sqrt(a^2+b^2). Note how this follows from the pythagorean theorem.
Answer:
<em>Grades to be scored in 3rd exam = 88</em>
Step-by-step explanation:
Given that average of 3 numbers is 85.
First two numbers are 81 and 86.
To find:
3rd number so that average is 85
Solution:
Let the third number = 
Formula for average is:

Here, sum of numbers = 
Total count of numbers = 3

<em>Grades to be scored in 3rd exam = 88</em>
45/2 can't be simplified.