Question

3. A bus covers a distance of 90 km at a uniform speed. Had the speed bean 15
more it would have taken 30 minutes less for the journey. Find the orginal speed of the bus​

Answer 1

Answer:

original speed=45 km/h

Step-by-step explanation:

let the speed be x km/h

time= distance/speed

time= 90/x

new speed= x+15 km/h

new time= 90/x+15

As per Question

=(90/x)-(90/x+15)= 30/60(1h= 60 sec)

90(1/x-1/x+15)=1/2

(x+15-x)/(x²+15x)= 1/(2*90)

15/(x²+15x=1/180

15×180= x²+15x

2700=x²+15x

x²+15x-2700=0

x²+60x-45x-2700=0

x(x+60)-45(x+60)=0

(x+60) (x-45)=0

x+60=0 or x-45=0

x=-60 or x=45

since speed cannot be negative

x= 45

original speed= 45 km/h