Answer:
a) 
D. 9.74
b) 
B. 74
Step-by-step explanation:
Part a
We have the following dataset given:
69 74 75 62 70 93 64 69 61 88 67 77 87 90 66 91 77 63 82 82 71 74 76 65 83
We can begin calculating the sample mean with the following formula:

And replacing we got:

Now we can calculate the sample deviation with the following formula:

And after replace we got:

Part b
For this case we need to sort the value on increasing way:
[1] 61 62 63 64 65 66 67 69 69 70 71 74 74 75 76 77 77 82 82 83 87 88 90 91 93
And the median would be the value in the position 13 and we got:

It is called a difference of squares because there are two things squared being subtracted. You can recognize it when there are two terms, subtraction between the two of them, and you know the square root of both
Answer:
Step-by-step explanation:
ill try this one in a few minutes for you.
Let's solve the equation:
9x+27 = 9(x+2)+9 ← Distribute 9 to the x and 2
9x+27 = 9x+18+9 ← Combine like terms
9x+27 = 9x + 27 ← Subtract 27 from both sides
9x = 9x
Infinitely many solutions would be correct because no matter what x is, it will always equal each other the both sides of the equation because it is 9 times x on both sides.