a motorist travels regularly between two towns. he usually takes 5 hrs when traveling at a certain speed,he finds out that if he increases his average speed by 15km/hr the journey takes one hour less. find his total speed

Answer 1

Let's assume the motorist's usual speed is 's' km/hr.

According to the given information, when the motorist travels at speed 's', the journey takes 5 hours. This can be represented as:

Distance = Speed * Time
d = 5s ...(1)

Now, when the motorist increases his speed by 15 km/hr, his new speed becomes 's + 15' km/hr. The journey now takes 1 hour less than before, which means it takes 4 hours. This can be represented as:

Distance = Speed * Time
d = 4(s + 15) ...(2)

Since the distances covered in both cases are the same (the motorist is traveling between the same two towns), we can equate equations (1) and (2):

5s = 4(s + 15)

5s = 4s + 60

5s - 4s = 60

s = 60

Therefore, the motorist's usual speed is 60 km/hr.

To find his total speed, we add the increase in speed of 15 km/hr to his usual speed:
Total speed = 60 km/hr + 15 km/hr = <<60+15=75>>75 km/hr.

Hence, his total speed is 75 km/hr.