Question

Out of 555 km total journey. bus travelled some distance with average speed 60 km/lu Then speed is increased by 15 km/hr. to complete the remaining journey to takes to complete the
total journey, Find the distance and time that the bus travelled by average speed 60 km/hr..

Answer 1

Answer:

The distance cover by bus traveled with average speed of 60 km/ h is 180 km

And , Time taken to cover 180 km with average speed of 60 km/h is 3 hours .

Step-by-step explanation:

Given as :

Total distance travelled by bus = D = 555 km

Let The distance cover with average speed 60 km/h = $d_1$ = d km

Let The distance cover with average speed of increased to 15 km/h = $d_2$ = 555 km - d km

So, The increased average speed = 60 km/h + 15 km/h = $s_2$ = 75 km/h

Let The time taken for average speed of 60 km/h = t hours

Let The time taken for average speed of 15 km/h = T hours

Total time taken to cover the total distance = 8 hours

According to question

∵ Distance = Speed × time

So, Time = $\dfrac{\textrm Distance}{\tetrm speed}$

Or, Total time = $\dfrac{d_1}{s_1}$ + $\dfrac{d_2}{s_2}$

Or, 8 = $\dfrac{d}{60}$ + $\dfrac{555 - d}{75}$

Or, 8 × 15 = $\dfrac{d}{4}$ + $\dfrac{555-d}{5}$

Or, 120 = $\dfrac{d}{4}$ + $\dfrac{555-d}{5}$

Or, 120 = $\dfrac{5 d + 4 (555 - d)}{20}$

or, 120 × 20 = 5 d - 4 d + 2220

Or, 2400 - 2220 = d

∴ d = 180 km

So, The distance cover by bus traveled with average speed of 60 km/ h = d = 180 km

Now,

time taken to cover 180 km with average speed of 60 km/h = $\dfrac{\textrm distance}{\textrm speed}$

Or, Time = $\dfrac{180}{60}$

i.e Time = 3 hours

So,  time taken to cover 180 km with average speed of 60 km/h = t = 3 hours

Hence,  The distance cover by bus traveled with average speed of 60 km/ h is 180 km

And , Time taken to cover 180 km with average speed of 60 km/h is 3 hours . Answer