The answer is 28.8 (the first option)
Answer: 3.712 hours or more
Step-by-step explanation:
Let X be the random variable that denotes the time required to complete a product.
X is normally distributed.

Let x be the times it takes to complete a random unit in order to be in the top 10% (right tail) of the time distribution.
Then, 
![P(z>\dfrac{x-3.2}{\sigma})=0.10\ \ \ [z=\dfrac{x-\mu}{\sigma}]](https://tex.z-dn.net/?f=P%28z%3E%5Cdfrac%7Bx-3.2%7D%7B%5Csigma%7D%29%3D0.10%5C%20%5C%20%5C%20%5Bz%3D%5Cdfrac%7Bx-%5Cmu%7D%7B%5Csigma%7D%5D)
As,
[By z-table]
Then,

So, it will take 3.712 hours or more to complete a random unit in order to be in the top 10% (right tail) of the time distribution.
Answer:
r = 5sec(θ)
Step-by-step explanation:
The usual conversion is ...
y = r·sin(θ)
x = r·cos(θ)
__
The second of these can be used here.
r·cos(θ) -5 = 0
r·cos(θ) = 5
r = 5/cos(θ) = 5sec(θ)
A suitable polar equation is ...
r = 5sec(θ)
9514 1404 393
Answer:
(b) 9
Step-by-step explanation:
The product of segment lengths to the near and far intersection with the circle is the same for both secants.
4(4+5) = 3(3+x) . . . . the above statement with numbers filled in
36 = 9 +3x . . . . . . . simplify
12 = 3 +x . . . . . . . . divide by 3
9 = x . . . . . . . . . . . subtract 3