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 some distance. find the average speed of aeroplane and the distance.
Answers
Answer:
If the average speed decreases by 120 km/hr & the time increase by 18 min and if the speed is increased by 180 km/hr & the time reduces by 18 mins then the average speed of the car is 720 km/hr and the distance travelled is 1080 km.
Step-by-step explanation:
Required formula:
Average Speed =
Let the average speed of the aeroplane be denoted by “x” km/hr and the distance travelled by it be denoted by “y” km/hr.
Step 1:
According to the first condition given in the question and based on the above formula, we can write the eq. as,
⇒ …… (i)
According to the second condition given in the question and based on the above formula, we can write the eq. as,
⇒ …… (ii)
Step 2:
On dividing the eq. (i) by (ii), we get
=
⇒ =
⇒ =
⇒ 120 (x+180) = 180 (x-120)
⇒ 2x + 360 = 3x - 360
⇒ x = 720 km/hr
Step 3:
Substituting the value of x = 720 km/hr in eq. (i), we get
y [] =
⇒ y [] =
⇒ y [] =
⇒ y = * (720*600) *
⇒ y = 1080 km
Thus, the average speed of the car is 720 km/hr and the distance travelled by it is 1080 km.