Final answer:
The constant of proportionality in the equation y = 2.5x is 2.5, indicating Nikoli makes 2.5 paper airplanes every 1 minute.
Step-by-step explanation:
The constant of proportionality in the equation y = 2.5x tells us the rate at which Nikoli makes paper airplanes. Since the equation represents the situation where Nikoli made 3 paper airplanes in 7.5 minutes, we can find the constant of proportionality by determining how many airplanes are made per minute. The equation can be interpreted as y (the number of airplanes made) equals 2.5 times x (the time in minutes).
To find the constant of proportionality, we can set y to 3 (the airplanes made) and x to 7.5 (the minutes taken). Plugging these values into the equation 3 = 2.5(7.5), we get 3 = 18.75. This means Nikoli makes airplanes at a rate of 2.5 per minute because the constant of proportionality is the coefficient of x in the equation.
Therefore, the constant of proportionality is 2.5. This means that Nikoli makes 2.5 paper airplane(s) every 1 minute(s).