Yes, the cost is proportional to the number of water bottles sold. 6 water bottles/$4.00 = 1.5 and 15 water bottles/$10.00 = 1.5.
The period of a sinusoid

is

, so any range such that

will give two complete periods.
Answer:
B
Step-by-step explanation:
The dot on 2 is an open spot, so 2 isn't part of the solution. the arrow points towards +∞ so, yeah. b