A motorist covers a distance of 39km in 45min by moving at a speed of x kmph for the first 15min, then moving at double the speed for the next 20 min, and then again moving at his original speed for the rest of the journey. Find x.
A. 60 km/h
B. 48 km/h
C. 36 km/h
D. 58 km/h
Answers
Answered by
19
#For the First 15 minutes (= 1/4 hours) of journey :
speed = x km/h
=> distance travelled in this part of journey = speed × time
= x× 1/4 = x/4 Km
_________________
#For Next 20 minutes (= 1/3 hours) of journey :
speed = 2x Km/h
(as speed becomes double;given )
=> distance travelled in this part of journey : (2x)×(1/3) = 2x/3 Km
_________________
#For next remaining time [ 10 minutes (=1/6 hours) ] of journey :
speed = x Km/h
( moves with original speed ;given)
=> distance travelled in this part of journey = x×1/6 = x/6 Km
_________________
The total distance the motorist cover = 39Km .
=>
(x/4)+(2x/3)+(x/6) = 39 Km
=> 13x = 39×12
=> x = 36 Km/h
__________________
So "C)" is the correct option .
__________________
hope it helps!
speed = x km/h
=> distance travelled in this part of journey = speed × time
= x× 1/4 = x/4 Km
_________________
#For Next 20 minutes (= 1/3 hours) of journey :
speed = 2x Km/h
(as speed becomes double;given )
=> distance travelled in this part of journey : (2x)×(1/3) = 2x/3 Km
_________________
#For next remaining time [ 10 minutes (=1/6 hours) ] of journey :
speed = x Km/h
( moves with original speed ;given)
=> distance travelled in this part of journey = x×1/6 = x/6 Km
_________________
The total distance the motorist cover = 39Km .
=>
(x/4)+(2x/3)+(x/6) = 39 Km
=> 13x = 39×12
=> x = 36 Km/h
__________________
So "C)" is the correct option .
__________________
hope it helps!
Answered by
1
Answer:
option number C is the correct answer
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