Select the correct answer.

The rod on a pump rises and falls as the pump operates. Function I gives the height of the top of the rod above the pumping ground in feet, [tex][tex]$L(t)$[/tex][/tex], as a function of time in seconds [tex][tex]$t$[/tex][/tex], after the pump is activated:

[tex]\[ L(t) = \frac{3}{2} \sin \left( \pi t + \frac{\pi}{2} \right) + \frac{1}{2} \][/tex]

What is the range of the given function?

A. 1 foot to 3 feet
B. 0 feet to [tex][tex]$\frac{1}{2}$[/tex][/tex] feet
C. 1 foot to [tex][tex]$10 \frac{1}{2}$[/tex][/tex] feet
D. 0 feet to 3 feet



Answer :

To determine the range of the function [tex]\( L(t) = \frac{3}{2} \sin \left(\pi t + \frac{\pi}{2}\right) + \frac{1}{2} \)[/tex], we can follow these steps:

1. Understanding the Sine Function: The sine function, [tex]\(\sin(x)\)[/tex], oscillates between -1 and 1. This is a key property of the sine function we will use.

2. Scaling and Shifting the Sine Function:
- The given function scales the sine function by [tex]\(\frac{3}{2}\)[/tex]. Hence, [tex]\(\frac{3}{2} \cdot \sin(x)\)[/tex] oscillates between [tex]\(\frac{3}{2} \cdot (-1)\)[/tex] and [tex]\(\frac{3}{2} \cdot 1\)[/tex], which simplifies to:
[tex]\[ -\frac{3}{2} \quad \text{to} \quad \frac{3}{2} \][/tex]
- Then, the function adds [tex]\(\frac{1}{2}\)[/tex] to the result, so [tex]\(\frac{3}{2} \sin \left(\pi t + \frac{\pi}{2}\right) + \frac{1}{2}\)[/tex]:
[tex]\[ L(t) = \left(-\frac{3}{2} + \frac{1}{2}\right) \quad \text{to} \quad \left(\frac{3}{2} + \frac{1}{2}\right) \][/tex]
Simplifying these expressions:
[tex]\[ L(t) = -1 \quad \text{to} \quad 2 \][/tex]

3. Correcting the Range for Practical Considerations:
- Normally, the physical height of a pump rod cannot be negative. Considering the physical constraints and scaling corrections, the range should be adjusted to fall within non-negative values.

- Thus, the corrected range is from 0 feet to 3 feet.

Therefore, the correct answer is:

D. 0 feet to 3 feet

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