let the distance be 200km
then
100km=30km/hr*t1 or t1=10/3 hr
and
100km=50km/hr*t2 or t2=2hr
avg speed= 200km/(16/3hr)=600/16=choice A
a car travels first half distance between two places with average speed of 30 km per hour and remaining half with a speed of 50 km per hour what is the average speed of the car is A 37.5KM/hr B 10km/hr //c// 42km/hr D 40km/hr
2 answers
d/2 = 30 t1 so t1 = d/60
d/2 = 50 t2 so t2 = d/100
t = t1 + t2
d = v (t1+t2) = v (d/60 + d/100)
100 = v ( 5/3 + 3/3) = (8/3) v
v = 300/8 = 37.5 km/hr
d/2 = 50 t2 so t2 = d/100
t = t1 + t2
d = v (t1+t2) = v (d/60 + d/100)
100 = v ( 5/3 + 3/3) = (8/3) v
v = 300/8 = 37.5 km/hr