Since the 3 and 7 have 21 as a common multiple you can divide 21 by the denominator of each term and then multiply it by the numerator which get you while numbers
Question 4 is d question 3 is c
Answer:
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Step-by-step explanation:
The function that could model this periodic phenomenon will be of the form

The tide varies between 3ft and 9ft, which means its amplitude
is

and its midline
is
.
Furthermore, since at
the tide is at its lowest ( 3 feet ), we know that the trigonometric function we must use is
.
The period of the full cycle is 14 hours, which means


giving us

With all of the values of the variables in place, the function modeling the situation now becomes

The amount of water that is needed to fill the pool is equal to the volume of the pool.
The pool is rectangular, with uniform depth so the volume of pool will be the product of its length , width and depth.
Thus,
Volume = 25 x 18 x 6 = 2700 ft³
This means, 2700 ft³ water is needed to fill the pool.