Question

Mr. Jackson had to attend a meeting in San Fransisco 300 miles from his home. He traveled the first 90 minutes at 64 miles per hour. The next hour he traveled 66 miles per hour. If he reached San Fransisco three hours later what was his average speed for the last three hours?

Answer 1

Let's call the average speed for the last three hours "S".

First, we need to find the total distance that Mr. Jackson traveled in the last three hours. He traveled 300 miles in total, and he covered 64 miles in the first 90 minutes, so he had 300 - 64 = 236 miles left to travel.

Next, we need to find the time he spent traveling in the last three hours. If he traveled for three hours, and the first hour he traveled at 66 miles per hour, then he covered 66 miles in the first hour. So, he had 236 - 66 = 170 miles left to travel in the last two hours.

Finally, we can use the formula for average speed: distance divided by time. The total distance he traveled in the last three hours was 170 miles, and the time he spent traveling was 2 hours, so his average speed for the last three hours was:

S = 170 miles / 2 hours = 85 miles per hour

So, Mr. Jackson's average speed for the last three hours was 85 miles per hour.

Answer 2

68 mph

Explanation:

Let's call the average speed for the last three hours "S".

The total distance traveled for the last three hours is 300 - 64 * 1.5 = 300 - 96 = 204 miles.

So, over the last three hours, Mr. Jackson covered a distance of 204 miles at a speed of S.

The time it took him to cover that distance is 3 hours.

We can use the formula distance = speed * time to find S:

204 = S * 3

Solving for S:

S = 68 mph

So the average speed for the last three hours was 68 mph.