Question

If the speedometer reading is 70 mph on your car and you have tires with a circumference of 103 inches, you are actually traveling ___ mph. (Factory-installed tires' circumference is 93 inches.

A) 70 mph
B) 73 mph
C) 75 mph
D) 78 mph

Answer 1

Changing the tire circumference from 93 inches to 103 inches results in a higher actual speed of 78 mph compared to the speedometer reading of 70 mph.

Step-by-step explanation:

The question is regarding how changing the circumference of the tires on a car can affect the actual speed compared to what the speedometer reads. Considering that the original tire circumference is 93 inches and the speedometer reads 70 mph, and the new tire circumference is 103 inches, we can calculate the actual speed. Because the new tires are larger, one revolution will cover more ground compared to the original tires.

Here's how to calculate the actual speed:

1. Determine the ratio of the new circumference to the original circumference: 103 inches / 93 inches = 1.1075.
2. Multiply the speedometer reading by this ratio to find the new actual speed: 70 mph * 1.1075 = 77.525 mph.

The actual speed of the car with the larger tires is approximately 78 mph, which corresponds to option D.