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:

 
        
             
        
        
        
Since the total measure of all the angles of a triangle is always 180, solve for x with the equation: 3x+1+2x-3+9x=180. x=13. Now plug in x and look for the smallest one, which will be B. 23 degrees.
        
             
        
        
        
Round 296 up to 300 and then divide 300 by 4 mentally.  Answer:  75.  Which is a more reasonable partial quotient, 50 or 70?
        
             
        
        
        
Answer:
53 cm.
Step-by-step explanation:
Circumference = pi times diameter 
We are trying to find diameter so rearrange
Circumference/pi = diameter
166.5/pi = 52.998596 
Approximately 53 centimeters of lace