Answer:
∠RST = 120°
Step-by-step explanation:
We assume the positions of the lines and angles will match the attached figure. The angle addition theorem gives a relation that can be solved for x, then for the value of angle RST.
∠RSU +∠UST = ∠RST
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78° + (3x -12)° = (6x +12)° . . . . . substitute given values into the above
54 = 3x . . . . . . . . . . . . . . . . divide by °, subtract 3x+12
108 = 6x . . . . . . . . . . . multiply by 2
120° = (6x +12)° = ∠RST . . . . add 12, show units
The measure of angle RST is 120 degrees.
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<em>Additional comment</em>
Note that we don't actually need to know the value of x (18) in this problem. We only need to know the value of 6x.
A set of data has a normal distribution with a mean of 5.1 and a standard deviation of 0.9. Find the percent of data between 4.2 and 5.1.
Answer: The correct option is B) about 34%
Proof:
We have to find 
To find
, we need to use z score formula:
When x = 4.2, we have:


When x = 5.1, we have:


Therefore, we have to find 
Using the standard normal table, we have:
= 

or 34.13%
= 34% approximately
Therefore, the percent of data between 4.2 and 5.1 is about 34%
The difference between 90% and 72% is 18%
Answer:
124°
Step-by-step explanation:
cos X = (11²+7²-16²)/2(11)(7)
= (121+49-256)/154
= -86/154
= -0.5584
X = cos~¹ -0.5584 = 124°