Answer:
There are 35 students in his class.
Step-by-step explanation:
1. Create a proportion: 60/100=21/x
2. Cross multiply, or not (I prefer to cross multiply). 60x=2100
3. Solve the equation: x=35.
Answer: There are 35 students in his class, 14 people going in school, 21 student online.
Answer: 
<u>Step-by-step explanation:</u>
Pythagorean Theorem is: a² + b² = c² , <em>where "c" is the hypotenuse</em>
<em />

Note: 4² + (8√2)² = hypotenuse² → hypotenuse = 12

Note: 12² + opposite² = 20² → opposite = 16

Note: adjacent² + 5² = 6² → adjacent = √11

Note: adjacent² + 7² = (13√2)² → adjacent = 17
The five digit number, 55,220 contains to 5's and two 2's. The 5's are in the ten thousand and one thousand columns. This means that one five represents 50,000 and the second represents 5, 000. The two's are in the hundreds and tens columns meaning one 2 represents 200 and the other 2 represents 20. In a direct comparison of these numbers the 5's equal 55,000 and the 2's equal 220.
As IQ scores for extensive populaces are focused at 100, the mean = 100.
There ought to be around half scores above or underneath the mean score since mean and middle is about a similar when the populace is substantial.
P(x > 100) = P( z> (100 - 100)/sd ) = P(z > 0)= 0.5
The number of the student who has scored over 100 = 0.5 x 78 = 39 Therefore the answer is 39 students.