So the mean is 72.97
We need to subtract the mean from each value and square it.
(65-72.97)^2= 63.5209
(68-72.97)^2=24.7009
(69-72.97)^2=15.7609
(70-72.97)^2=8.8209
(71-72.97)^2= 3.8809
(72-72.97)^2=0.9409
(90-72.97)^2=290.0209
(95-72.97)^2=485.3209
Now we add up the new values ( also consider their frequency) and find their mean.
Add the values
63.5209+(2 •24.7009=49.4018)+(5•15.7609=78.8045)+(8•8.8209=70.5672)+(7•3.8809=27.1663)+(3•0.9409=2.8227)+(2•290.0209=580.0418)+(2•485.3209=970.6418)= 1,842.967
Divide by total numburs to find the mean
1,842.967/ 30=61.43223333
The standar deviation is the square root of the mean so is
Square root of 61.43223333=7.837871735
Round to the nearest tenth
Standard Deviation is 7.8
There is no solution to this system of linear equations
Answer:
Option (3)
Step-by-step explanation:
w = ![\frac{\sqrt{2}}{2}[\text{cos}(225) + i\text{sin}(225)]](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csqrt%7B2%7D%7D%7B2%7D%5B%5Ctext%7Bcos%7D%28225%29%20%2B%20i%5Ctext%7Bsin%7D%28225%29%5D)
Since, cos(225) = cos(180 + 45)
= -cos(45) [Since, cos(180 + θ) = -cosθ]
= -
sin(225) = sin(180 + 45)
= -sin(45)
= -
Therefore, w = ![\frac{\sqrt{2}}{2}[-\frac{\sqrt{2}}{2}+i(-\frac{\sqrt{2}}{2})]](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csqrt%7B2%7D%7D%7B2%7D%5B-%5Cfrac%7B%5Csqrt%7B2%7D%7D%7B2%7D%2Bi%28-%5Cfrac%7B%5Csqrt%7B2%7D%7D%7B2%7D%29%5D)
= 
= 
z = 1[cos(60) + i(sin(60)]
= 
= 
Now (w + z) = 
= 
= 
= 
Therefore, Option (3) will be the correct option.
Answer: 43 degrees
Step-by-step explanation:
cos A = 8/11
cos-1 = 43.3417