Multiple choice

Two cars started from the same point and travelled on a straight course in opposite directions for exactly 2 hours. At that time they were 208 miles apart. If one car, is faster than the other car by an average of 8 miles per hour, what was the average speed (in miles/hr) of the slower car for the two hour trip?

  1. 32 miles per hour

  2. 40 miles per hour

  3. 48 miles per hour

  4. 56 miles per hour

  5. 60 miles per hour
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C Correct answer
Explanation

Let the speed of the slower car be x. The faster car's speed is x+8. In 2 hours, the total distance covered by both is 2(x) + 2(x+8) = 208. Solving 4x + 16 = 208 gives 4x = 192, so x = 48.

AI explanation

Using the relative speed formula for objects moving in opposite directions, the relative speed is the sum of their individual speeds, so 208 miles divided by 2 hours equals 104 miles per hour. Let the speed of the slower car be x, which makes the faster car's speed x plus 8. Therefore, x plus x plus 8 equals 104, which simplifies to 2x equals 96 and x equals 48. The average speed of the slower car is 48 miles per hour.

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