Answer:

B is right answer.

i hope it will help you

Step-by-step explanation:

Let the time taken to reach the destination be 3x hours.

Total distance = 40 * 3x = 120x km

He covered 2/3 * 120x = 80x km in 1/3 * 3x = x hours

So, the remaining 40x km, he has to cover in 2x hours. Required speed = 40x/2x = 20 kmph

Verified answer

Given:

• By travelling at 40 kmph, a person reaches his destination on time. He covered two-third the total distance in one-third of the total time.

To find:

• What speed should he maintain for the remaining distance to reach his destination on time?

Concept:

• Speed is defined as the rate of change of position of an object in any direction. It's calculated as the distance travelled divided by the amount of time it took to travel that distance.

[tex]\;\red{\boxed{\gray{\;\textsf{\textbf{Speed}}=\dfrac{\textsf{\textbf{Distance}}}{\textsf{\textbf{Time taken}}}\;}}}

[/tex]

Calculations:

• Let us assume that, the time taken to reach the destination be 3t hours.

• We know, the distance is the product of speed and time covered by the vehicle.

So, total distance = 40 × 3t = 120t km.

As it is given that, he covered two-third the total distance in one-third of the total time.

Therefore,

[tex] = \frac{2}{3} \times 120t[/tex]

[tex] = 2 \times 40t[/tex]

[tex] = 80[/tex]

And ,

[tex] = \frac{1}{3} \times 3t[/tex]

[tex] = 1 \times t[/tex]

,

[tex] = t[/tex]

• So, now, he covered 80t km distance in t hours time.

So, the remaining distance 120t - 80t = 40t km, he has to cover in 3t - t = 2t hours time.

• Distance = 40t km

• Time taken = 2t hours time

[tex]speed = \frac{distance}{time \: taken} [/tex]

[tex]speed = \frac{40t}{2t} [/tex]

[tex]speed = \frac{40}{2} [/tex]

speed =20kmph

• Hence the required speed to reach the destination on time is20kmph

so, option (B) is the correct