Final answer:
There are two quiet spots along the line segment connecting the speakers.
Step-by-step explanation:
The number of quiet spots (completely destructive interference) along the line segment connecting the speakers can be calculated using the formula:
n = d / λ
Where 'n' is the number of quiet spots, 'd' is the distance between the speakers (7.0 m in this case), and λ is the wavelength of the pure tone (3.6 m in this case).
Plugging in the values, we get:
n = 7.0 / 3.6
Simplifying, we find that there are approximately 1.94 quiet spots. Since we cannot have fractional quiet spots, the answer is that there are two quiet spots along the line segment connecting the speakers.