Question

A car driver went a mile in 5 minutes with the wind and returned in 7 minutes against the wind. How fast could he drove a mile if there was no wind? (speed in miles/second) 7/12 5/12 2/7 3/7

Answer 1

The speed of the car with no wind is 0.17145 miles per minute (approximately 0.01429 miles per second).

Step-by-step explanation:

Let's first calculate the speed of the car with the wind. We know that the distance traveled is 1 mile and the time taken is 5 minutes. Speed equals distance divided by time, so the speed of the car with the wind is 1 mile / 5 minutes = 0.2 miles per minute.

Now, let's calculate the speed of the car against the wind. Again, the distance traveled is 1 mile, but the time taken is 7 minutes. So, the speed of the car against the wind is 1 mile / 7 minutes = 0.1429 miles per minute.

To find the speed of the car with no wind, we can use the concept of relative velocity. The speed of the car with the wind is the speed of the car with no wind plus the speed of the wind, and the speed of the car against the wind is the speed of the car with no wind minus the speed of the wind.

Let's assume the speed of the car with no wind is x miles per minute and the speed of the wind is y miles per minute.

Using these assumptions, we can set up the following equations:

x + y = 0.2 (equation 1)

x - y = 0.1429 (equation 2)

Now, add equation 1 and equation 2:

2x = 0.3429

Solving for x, we get:

x = 0.3429 / 2 = 0.17145 miles per minute.

Therefore, the car could drive a mile with no wind at a speed of 0.17145 miles per minute (or approximately 0.01429 miles per second).