# A plane left 30 minutes later than the scheduled time. In order to reach the destination 1500 km away in time, it has to increase the speed by 250 km/hr from the usual speed. Find its usual speed.

By Ritesh|Updated : November 13th, 2022
1. 1000 km/hr
2. 750 km/hr
3. 800 km/hr
4. 680 km/hr

The usual speed is B. 750 km/hr. Steps to find the usual speed:

Let the plane's normal speed be x km/hr and its increased speed be y km/hr.

y = (x + 250) km/hr

Distance = 1500 km/hr

According to the question we can write as,

(Scheduled time) - (time taken at increased speed) = 30 minutes = 0.5 hours.

Substituting the values we get:

1500/x - 1500/y = ½

1500/x - 1500/(x + 250) = ½

We know that time = distance/speed:

(1500x + 375000 - 1500x)/ x (x + 250) = ½

x (x + 250) = 750000

On simplification we get:

x2 + 250 x - 750000 = 0

x2 + 1000 x - 750 x - 750000 = 0

x (x + 1000) - 750 (x + 1000) = 0

(x + 1000) (x - 750) = 0

x = 750 or x = -1000

But speed can never be a bad thing. A 750 km/hr average speed is used.

The most crucial scientific notion is measurement. Base or physical fundamental units are used to quantify a wide range of quantifiable quantities. One such measurable metric is speed, which calculates the ratio between the distance an object travels and the time needed to cover that distance. The speed at which an object's location changes in any direction.

Summary:

## A plane left 30 minutes later than the scheduled time. In order to reach the destination 1500 km away in time, it has to increase the speed by 250 km/hr from the usual speed. Find its usual speed. (a)1000 km/hr (b)750 km/hr (c)800 km/hr (d)680 km/hr

A plane left 30 minutes later than the scheduled time. In order to reach the destination 1500 km away in time, it has to increase the speed by 250 km/hr from the usual speed. The usual speed is 750 km/hr.