Question

(i) If the speed of an aeroplane is decreased by 120 km/h, it takes 18 minutes more
to travel some distance. If the speed is increased by 180 km/h, it takes 18 minutes
less to travel the same distance. Find the average speed of the aeroplane and the
distance.​

Answer 1

Answer:

Step-by-step explanation:

LET THE DISTANCE BE X

TIME BE T

SPEED=DISTANCE /TIME

CASE 1:

120=X/(T+(18/60))

120=X/(T+0.3)

X= 120T +36 (1ST EQUATION)

CASE 2:

180=X/(T-(18/60))

180(T-0.3)=X (2ND EQUATION)

FROM 1 AND 2

120T+36=180T-54

60T=90

T=1.5 HRS

X=12*18

  =216 KM

AVERAGE SPEED =216/1.5

                              =144 KM/HR