A car covers first half of certain journey with speed of 50 km/h and second half journey with speed of 40 km/h. If it takes 9 hours to cover total distance. What is the distance covered in whole journey

Let's solve this problem step by step:

Step 1: Let's assume the total distance covered in the whole journey is "d" kilometers.

Step 2: The car covers the first half of the journey at a speed of 50 km/h. So, the time taken to cover the first half of the journey can be calculated using the formula: time = distance / speed. Therefore, the time taken to cover the first half of the journey is d/2 / 50 = (d/2) * (1/50) = d/100 hours.

Step 3: The car covers the second half of the journey at a speed of 40 km/h. So, the time taken to cover the second half of the journey can be calculated using the same formula: time = distance / speed. Therefore, the time taken to cover the second half of the journey is d/2 / 40 = (d/2) * (1/40) = d/80 hours.

Step 4: The total time taken to cover the whole journey is given as 9 hours. So, we can write the equation: (d/100) + (d/80) = 9.

Step 5: To solve this equation, we can find a common denominator for the fractions. The common denominator for 100 and 80 is 400. So, we can rewrite the equation as: (4d/400) + (5d/400) = 9.

Step 6: Combining the fractions, we get: (9d/400) = 9.

Step 7: To isolate "d", we can multiply both sides of the equation by 400/9. This gives us: d = (9 * 400) / 9 = 400 kilometers.

Therefore, the distance covered in the whole journey is 400 kilometers.