On his outward journey, Ali travelled at a speed of s km/h for 2.5 hours. On his return journey, he increased his speed by 4 km/h and saved 15 minutes. Find Ali's average speed for the whole journey.

3.08 km/h.

Step-by-step explanation:

We know that,

Ali traveled at a speed of s km/h for 2.5 hours.

Let d be the distance and t be the time.

     ...(1)

On his return journey, he increased his speed by 4 km/h and saved 15 minutes. So, distance is d and times is t-15.

     ...(2)

From (1) and (2), we get

Put t=40 in (1).

So, t=40 and d=100.

Now,

Total distance = d + d = 100 + 100 = 200

Total time = t + t - 15 = 40 + 40 - 15 = 65

So, the average speed is

Therefore, the average speed is 3.08 km/h.

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step-by-step explanation:

because i said it is

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°