Reno, Nevada and Salt Lake City, Utah are about 400 miles apart today. Yet 15 million years ago they were only 250 miles apart. The continental crust is being stretched by plate tectonic forces. How many inches per year do the two cities move away from each other?

Convert 150 miles to inches and divide by 15*10^6 (15 million).

1 mile = 63,360 inches.

• 1 mile=5280 feet

• 1 foot=12 inches

• 5280 X 12 = 63,360 inches in 1 mile

• 400 x 63,360 = 25,344,000 inches in 400 miles (this is how many inches SLC and Reno are apart today.

• 250 x 63,360 = 15,840,000 inches in 250 miles (this is how many inches SLC and Reno were apart 15,000,000 years ago.

• 25,344,000 – 15,840,000 = 9,504,000 inches (this is the difference in inches from current day and 15,000,000 years ago of the location of the two cities).

• 9,504,000/15,000,000 = approximately .6336 inches per year!

To determine how many inches per year Reno, Nevada, and Salt Lake City, Utah move away from each other, let's calculate the average rate of movement over 15 million years.

First, let's find the difference in the current distance and the distance 15 million years ago:

Current distance = 400 miles
Distance 15 million years ago = 250 miles

Difference in distance = Current distance - Distance 15 million years ago
Difference in distance = 400 miles - 250 miles
Difference in distance = 150 miles

Now, we need to convert the difference in distance to inches. Since there are 5,280 feet in a mile and 12 inches in a foot, we can calculate the total number of inches:

Total inches = Difference in distance * 5,280 feet/mile * 12 inches/foot
Total inches = 150 miles * 5,280 feet/mile * 12 inches/foot

Simplifying the calculation:

Total inches = 150 * 5,280 * 12
Total inches = 9,504,000 inches

Finally, we divide the total number of inches by 15 million years to find the average rate of movement per year:

Average rate of movement = Total inches / 15,000,000 years
Average rate of movement = 9,504,000 inches / 15,000,000 years

Calculating the average rate of movement per year:

Average rate of movement = 0.6336 inches per year

Therefore, the two cities, Reno, Nevada, and Salt Lake City, Utah, move away from each other at an average rate of approximately 0.6336 inches per year due to the stretching of the continental crust by plate tectonic forces.