A man walks on a straight road from his home to a market 2.5 𝑘𝑚 away with a speed of 5 𝑘𝑚/ℎ. Finding the market closed, he instantly turns and walks back home with a speed of 7.5 𝑘𝑚/ℎ. The average speed of the man over the interval of time 0 to 40 𝑚𝑖𝑛. Is equal to

Question : A man walks on a straight road from his home to a market 2.5 𝑘𝑚 away with a speed of 5 𝑘𝑚/ℎ. Finding the market closed, he instantly turns and walks back home with a speed of 7.5 𝑘𝑚/ℎ. The average speed of the man over the interval of time 0 to 40 𝑚𝑖𝑛. Is equal to