Answer:
a) The probability that at least 5 ties are too tight is P=0.0432.
b) The probability that at most 12 ties are too tight is P=1.
Step-by-step explanation:
In this problem, we could represent the proabilities of this events with the Binomial distirbution, with parameter p=0.1 and sample size n=20.
a) We can express the probability that at least 5 ties are too tight as:

The probability that at least 5 ties are too tight is P=0.0432.
a) We can express the probability that at most 12 ties are too tight as:

The probability that at most 12 ties are too tight is P=1.
Answer:
(i) The name of the part of the circle, OQ is a radius
(ii) The radius of the sector QOR is 21 cm
Step-by-step explanation:
The given figure is a sector of the circle O
∵ Any sector of a circle formed from 2 radii and an arc
∴ OQ is a radius
(i) The name of the part of the circle, OQ is a radius
The rule of the length of an arc of a circle is L =
× 2 π r, where
- α is the angle of the sector
- r is the radius of the circle
∵ The length of the arc QR is 22 cm
∴ L = 22
∵ The measure of the angle of the arc is 60°
∴ α = 60°
∵ π = 
→ Substitute them in the rule above
∵ 22 =
× 2 ×
× r
∴ 22 =
r
→ Divide both sides by 
∴ 21 = r
(ii) The radius of the sector QOR is 21 cm
Refer to the diagram shown below. It shows a vertical cross-section of the paraboloid through its axis of symmetry.
Let the vertex of the parabola be at the origin. Then its equation is of the form
y = bx²
Because the parabola passes through (18,8), therefore
8 = b(18²)
b = 0.02469
The parabola is y = 0.02469x².
The receiver should be placed at the focal point of the paraboloid for optimal reception.
The y-coordinate of the focus is
a = 1/(4b) = 1/0.098765 = 10.125 in
Answer: The receiver is located at 10.125 inches from the vertex.