Miriam left chicago at 9: 00 am and headed to washington. the first 2 hour miriam averaged 70 mph. but after she decided to reach washington at 6: 00 pm, she increased her speed. what was her speed after increasing, if the distance between the cities is 700 miles.

80 mph

Step-by-step explanation:

step 1

Find the distance traveled by Miriam the first two hours

Remember that the distance is equal to the speed multiplied by the time

we have

so

9:00 AM +2 h=11:00 AM

At 11:00 am Miriam has travel 140 miles

step 2

Find out the speed

Remember that the speed is equal to divide the distance by the time

The time is equal to

6:00 PM-11:00 AM=7 h

the distance is equal to

700-140=560 miles

therefore

536

step-by-step explanation: