a man travels some distance at a speed of 12km/hr and returns at 9km/hr .if the total time taken by him is 2hrs 20 min ,find the distance.
How 36 came
To find the distance, we'll use the formula:
Distance = Speed x Time
Let's assume the distance traveled by the man is "D" km.
Given:
Speed of the man while going = 12 km/hr
Speed of the man while returning = 9 km/hr
Total time taken by the man = 2 hours 20 minutes, which is equivalent to 2 + 20/60 hours, or 2.33 hours.
Since the man traveled the same distance while going and returning, we can write the equation:
D/12 + D/9 = 2.33
To solve this equation, we'll first find a common denominator for the fractions (36 in this case) and then simplify the equation:
(3D + 4D)/36 = 2.33
7D/36 = 2.33
Now, we'll cross-multiply to isolate the variable:
7D = 2.33 * 36
7D = 83.88
Finally, we'll solve for D by dividing both sides of the equation by 7:
D = 83.88 / 7
D ≈ 11.98
Therefore, the distance traveled by the man is approximately 11.98 km.
time for first part = d/12
time for return = d/9
d/12 + d/9 = 7/3
times 36
3d + 4d = 84
7d = 84
d = 12
the distance was 12 km