10C4 represent the Combinations of 10 objects taken 4 at a time.
The formula for nCr is:

In the given case, n=10 and r=4. Using these values we get:

This means we can make 210 combinations of 10 objects taken 4 at a time.
Answer:
(n - 8n)(m+8n)
Step-by-step explanation:
x² - y² = (x - y)(x + y)
In this situation, the "x" = m and the "y" = 8n
So,
m² - 64n² = (n - 8n)(m+8n)
Answer:
0.8594
Step-by-step explanation:
Let a denote the event of forgetting to shut off machine and b be the event of being defective.
-A foreman forgets to shut off machine 55% of the time.
-If he forgets, 15% of molds are defective.
-If he does not, 3% of molds are defective.
#The probability that he forgot to shut off the machine is calculated as:

P(a and ~b)=0.55(1-0.15)=0.4675
P(~a and b) = (1-0.55)*0.03=0.0135
P(~a and ~b) = (1-0.55)*(1-0.03)=0.4365
#Conditional probability is defined as:

Hence, the probability that the foreman forgot to shut off the machine the previous night is 0.8594
The first one, SAS Postulate