Question

David covered 40% of a certain distance at 20 km/hr, 50% of the remaining distance at 10 km/hr and the rest at 30 km/hr.The total travelled time is 8 hours, then find the total distance covered by him.​

Answer 1

Answer:

400/3 km

Step-by-step explanation:

let x be total distace.

40% of x = 2x/5

remaining distance = 3x/5

50% of 3x/5 = 3x/10

remaining distance = 3/10 x

total time = 8 hr

t1+ t2+ t3 = 8hr

2x/100 + 3x/100 + 3x/300 = 8

6x/100 = 8

x = (8×100) /6

= 800/6

= 400/3 km

Answer 2

Answer:

The distance travelled is $400/3$km.

Step-by-step explanation:

It is given that David covered $40$% of a certain distance at $20 km/hr$, $50$% of the remaining distance at $10 km/hr$ and the rest at $30 km/hr$.

Assuming $x$ be total distance,

$40$% of $x=\frac{2x}{5}$

Remaining distance is $\frac{3x}{5}$

So, $50$% of $\frac{3x}{5} =\frac{3x}{10}$

Remaining distance is $\frac{3x}{10}$.

Total time is $8h$

Sum of three times $=8$

Using Time = Distance /Speed, we get

$8=\frac{2x}{100} +\frac{3x}{100} +\frac{2x}{300}$

$6x/100=800$

$x=400/3km$.

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