Question

1] Some part of journey of 555 km was completed by a car with speed 60 km/hr. Then the speed is increased
by 15 km/hr and the journey is completed. If it takes 8 hours to reach, find the time taken and distance
covered by 60 km/hr. Ans :[It takes 3 hours and the distance covered at the speed of 60 km/h is 18 km
Lem.​

Answer 1

Answer:

The distance covered with the speed 60 km/hr is 180 km. and the corresponding time taken is 3 hours.

Step-by-step explanation:

Let x km be the distance covered with the speed 60 km/hr and t be the time taken for that journey.

Since the total duration is 8 hours, the time taken for the remaining journey is 8 - t and the remaining distance is 555 - x km.

Now, from the formula  $time = \frac{distance}{speed}$, we have

$t = \frac{x}{60}$ and

$8 - t = \frac{555-x}{75}$

Note that the increased speed is 60 + 15 = 75 km/hr.

Now,

$t + (8-t) = \frac{x}{60} + \frac{555-x}{75}$

$8 = \frac{5x+(2220-4x)}{300}$

8 × 300 = 2220 + x

x = 2400 - 2220

= 180

and t = 180/60 = 3 hours

Hence, the distance covered with the speed 60 km/hr is 180 km. and the corresponding time taken is 3 hours.

Answer 2

Answer:

The distance covered with the speed 60 km/hr is 180 km. and the corresponding time taken is 3 hours.

Step-by-step explanation:

Let x km be the distance covered with the speed 60 km/hr and t be the time taken for that journey.

Since the total duration is 8 hours, the time taken for the remaining journey is 8 - t and the remaining distance is 555 - x km.

Now, from the formula time = \frac{distance}{speed}time=

speed

distance

, we have

t = \frac{x}{60}t=

60

x

and

8 - t = \frac{555-x}{75}8−t=

75

555−x

Note that the increased speed is 60 + 15 = 75 km/hr.

Now,

t + (8-t) = \frac{x}{60} + \frac{555-x}{75}t+(8−t)=

60

x

+

75

555−x

8 = \frac{5x+(2220-4x)}{300}8=

300

5x+(2220−4x)

8 × 300 = 2220 + x

x = 2400 - 2220

= 180

and t = 180/60 = 3 hours

Hence, the distance covered with the speed 60 km/hr is 180 km. and the corresponding time taken is 3 hours.