Question

Time taken to travel a certain distance 'x' km at speed of 40 km/hr is 4 hours more than the time taken to travel (x+20) km at speed of 80 km/hr. Find the time taken to travel (x +80) km at the speed of 60 km/hr?
(a) 8 hours
(b) 6 hours
(c) 5 hours
(d) 4 hours
(e) 7 hours
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Answer 1

Answer:   The time take to travel 420 km is =  7 hours

Explanation:- The time taken to travel (x+20) km at speed of 80 km/hr.

                           Distance = speed × Time

                           ( x+20) = 80 × Time

                             Time =  $\frac{( x+20)}{80}$

Given - Time taken to travel a certain distance 'x' km at speed of 40 km/hr. is 4 hours more than the time taken to travel (x+20) km at speed of 80 km/hr.

So ,      Distance = speed × Time

               x = 40 × ( $\frac{( x+20)}{80}$ + 4)

               $\frac{x}{40}$ = $\frac{( x+20)}{80}$ +4

               $\frac{x}{40}$ = $\frac{x + 20 +320}{80}$ (taking LCM)

             $x$ × 80 = 40 ( $x$ + 340)

             $x$ × 80 = 40$x$+ 13600)

                80$x$ - 40$x$ = 13600

                         40$x$ = 13600

                           $x$ = 13600/40

                           $x$ = 340

the time taken to travel (x +80) km at the speed of 60 km/hr.

 Distance = speed × Time

    (x +80) = 60 × Time

     (340+80) = 60 × Time

        420 =  60 × Time

          Time = 420/60

             Time = 7 hours