Answer:
He can grade 1.25 assignments in 1 minute.
Step-by-step explanation:
Because the teacher can grade 25 assignments in 20 minutes, we can dive 25 by 20 to get the constant rate.

So he can grade 1.25 assignments in 1 minute.
This is the number of combinations of 2 from 23
23C2 = 23! / 2! 21!
A quick way to do this is 23*22 / 2 = 253
Answer:
The fourth of twenty is 5
Step-by-step explanation:
The 4th of twenty implies that we divide the number twenty into 4 place, let's us divide it 4
20/4= 5
This problem bothers on on division of numbers and it requires proper understanding of words/terms associated with it.
The area of a circle is equal to:

r = 1/2 the diameter
1/2 of 14 is 7
7 squared is 49
<em><u>The area is 49π</u></em>
Answer:
$930
Step-by-step explanation:
450 + 9600(.05)
450 + 480
$930