The rule for the sequence is: You add 4/6 each time
5/6 +4/6 = 1 1/2
1 1/2 + 4/6 = 2 1/6
2 1/6 +4/6 = 2 5/6
Question is missing:
"What is the gravitational force between the Sun and Jupiter?"
Answer:

Explanation:
The gravitational force between two objects is given by

where
is the gravitational constant
m1, m2 are the masses of the two objects
r is the separation between the objects
In this problem, we have
is the mass of the sun
is the mass of Jupiter
is their separation
Solving the equation, we find

-- The unit of frequency is "per second" (Hz), which is [reciprocal time].
-- The unit of period is "second", which is [time].
Do you see where this is going ?
'Frequency' and 'period' are reciprocals of each other.
For any wave ...
Period = (1) / (frequency) .
Frequency = (1) / (period) .
Answer: B
Explanation: This can be easily done by inputting 5280 * 2.2.