Question

A train covers a distance of 90 kms at a uniform speed. It would have taken 30 minutes less if the speed had been 15km/hr more. Calculate the original duration of the journey.

Answer 1

Answer:

Step-by-step explanation:

 

Let the original speed of train be km/h.

then increased speed  km/hr                                                            

usual time hours                                                                                

New timehours

According to the question

                                                                                           

begin mathsize 12px style straight x squared plus 15 straight x minus 2700 equals 0

straight x squared plus 60 straight x minus 45 straight x minus 2700 equals 0

straight x open parentheses straight x plus 60 close parentheses minus 45 open parentheses straight x plus 60 close parentheses equals 0

open parentheses straight x plus 60 close parentheses open parentheses straight x minus 45 close parentheses equals 0

straight x equals negative 60 space or space 45 end style

                               

         

Rejecting the negative value, we have x = 45

Hence usual speed of train = 45 km/hr.

Answer 2

I think the answer would be:

x= 45km/he