Answer:
Average speed of passenger aircraft in 1978 is 408.9 mph
Explanation:
Here, in the question, we are tasked with giving the value of the average speed of the passenger aircraft in the US for the year 1978, given that it is a certain multiple of the value in 1960.
So what we will be doing here is to get the value of the average speed and it can be gotten by multiplying the average speed in 1960 by the multiple to which the speed is, now in 1978.
From the question, we can write a formula for this;
Average speed of passenger aircraft in 1978 = 1.74 * average speed of passenger aircraft in 1960
From the question, we have that the average speed of passenger aircraft in 1960 = 235 mph
Thus,
Average speed of passenger aircraft in 1978 = 1.74 * 235 = 408.9 mph