Robbi rides her bicycle uphill for three miles at 8 mph. She then rides on level ground for seven miles at 14 mph. She continues downhill for twelve miles at 24 mph. What is her average speed in miles per hour for the entire trip?

Average speed of Robbi = 16 mph

Step-by-step explanation:

Formula for the average speed is,

Average speed =

Total distance covered by Robbi = 3 + 7 + 12

                                                       = 22 miles

Time taken to cover 3 miles =

                                               = hours

                                               = 0.375 hours

Time taken to cover 7 miles =

                                               = 0.5 hours

Times taken to cover 12 miles =

                                                  = 0.5 hours

Total time taken to cover the entire trip = 0.375 + 0.5 + 0.5

                                                                  = 1.375 hours

Average speed of Robbi =

                                         = 16 miles per hour

a. 12.5 kg

step-by-step explanation:

f = ma

so

m = f/a = (2500 n)/(200 m/s²) = 12.5 kg

1 n = 1 kg·m/s²