51 hours=........days 5 minutes 27 seconds : 3 = .......... seconds. How fast is Anna going if she runs 8 miles in the park in only 2 hours? How fast is Jack going if the train he is on travels 20 miles in just 6 minutes? How far will Mary travel if she rides her motorbike for 24 minutes at a speed of 75 miles/hour? Yesterday Peter roller skated for 2.5 hours at a speed of 6 km/h. How many kilometers did he skate?

1. 51 hours = 2 days and 3 hours. (There are 24 hours in a day, so divide 51 by 24 to get the number of days, which is 2, and the remainder is 3 hours.)

2. 5 minutes 27 seconds : 3 = 1 minute and 49 seconds. (Divide the total time by 3 to get the average time, which is 1 minute and 49 seconds.)

3. Anna's speed is 4 miles per hour. (Divide the total distance by the total time: 8 miles / 2 hours = 4 miles/hour.)

4. Jack's speed is 200 miles per hour. (Convert the time to hours: 6 minutes = 6/60 = 0.1 hours. Divide the total distance by the total time: 20 miles / 0.1 hours = 200 miles/hour.)

5. Mary will travel 30 miles. (Multiply the speed by the time: 24 minutes = 24/60 = 0.4 hours. Multiply the speed by the time: 0.4 hours * 75 miles/hour = 30 miles.)

6. Peter skated 15 kilometers. (Multiply the speed by the time: 2.5 hours * 6 km/h = 15 kilometers.)

1) 51h=2day3h

2) 5 minutes 27 seconds : 3=1min49s

3) v=s/t   2h=7200s

=> 8/7200=1/900(m/s)

4) 6min = 360s

v=s/t

=> 20/360=1/18(m/s)

5) v=s/t => s=v.t  đổi 24h=0,4min

=>0,4x75=30miles

6) v=s/t => s=v.t

=>2,5x6=15m