Mr. Suki plans to drive 900 miles to his farmhouse, driving an average of 50 miles per hour. How many miles per hour faster must he average, while driving to reduce his total driving time by 3 hours?

900 miles at 50 miles an hour will take him 900/50=18 hours. He wants to do it in 15 hours, so he's going to have to travel at 900/15=60 miles an hour. If he does that, he'll have increased his speed by 10 mph.

To find out how many miles per hour faster Mr. Suki must average to reduce his total driving time by 3 hours, we need to compare his current driving time with the time it would take if he drove 3 hours less.

Let's start by calculating his current driving time. We can use the formula: Time = Distance / Speed.

The distance Mr. Suki plans to drive is 900 miles, and his current average speed is 50 miles per hour.

Current driving time = 900 miles / 50 miles per hour = 18 hours.

Now, let's find out the time it would take if Mr. Suki drove 3 hours less. We subtract 3 from his current driving time.

Desired driving time = Current driving time - 3 hours = 18 hours - 3 hours = 15 hours.

To calculate the average speed needed to achieve the desired driving time, we can rearrange the formula: Speed = Distance / Time.

Let's use the formula with the desired driving time of 15 hours and the same distance of 900 miles.

Speed = 900 miles / 15 hours = 60 miles per hour.

Therefore, Mr. Suki must average 60 miles per hour to reduce his total driving time by 3 hours. This means he must drive 10 miles per hour faster than his current average speed.