Question

An airplane flew for 8 hours at an airspeed of x miles per hour (mph), and for 7 more
hours at 325 mph. If the average airspeed for the entire flight was 350 mph, which of
the following equations could be used to find x ?
A. x + 325 = 2(350)
B. x + 7(325) = 15(350)
C. 8x – 7(325) = 350
D. 8x + 7(325) = 2(350)
E 8x + 7(325) = 15(350)

Answer 1

av speed = total distance / total time

 350 = 8x + 7 (325) / 8 +7  = 15 (350) = 8x + 7(325)


hence option E is correct.

Answer 2

hello friend
Average speed= total distance/ total time taken
350= 8x +( 325× 7) / 15
15× 350 = 8x +( 325 )7
S= D/ T
D= S× T
answer is option E
hope it helps u..........