Answer:
a) t = 4000/v
b) t = 4000/(v + 20)
c) see attached workings
Step-by-step explanation:
a) A man jogs 4 km everyday at an average speed of v m/min
As the speed is measured in meters per minute, we need to convert the distance (4 km) into meters:
1 km = 1000 m
⇒ 4 km = 4 x 1000 = 4000 m
distance = speed x time
⇒ time = distance / speed
⇒ t = 4000/v (where t = time in minutes)
b) If his average speed increased by 20 m/min, then his speed would now be (v + 20) m/min
⇒ t = 4000/(v + 20) (where t = time in minutes)
c) Given the man would take 3 min less if his average speed increased by 20 m/min, we can rewrite the second equation as:
t - 3 = 4000/(v + 20)
Now simply substitute the first equation t = 4000/v into the second:
(I have typed this used MS Word and attached, as the equation editor here in Brainly is not working at the moment).
