Step-by-step explanation:
Since Bridget rows 1 hour 4 kilometers upstream and 30 minutes (half of one hour) kilometers, downstream, then we have to find the average speed of both times. First, let's find how long Bridget would have to row upstream every kilometer.
Step 1:
60 minutes ÷ 4 kilometers = 15 minutes per kilometer (upstream)
30 minutes ÷ 4 kilometers = 7.5 minutes per kilometer (downstream)
Step 2:
Now, we find the average of 15 and 7.5. To do that, we add the values together and divide them by the number of values there are (2).
15 + 7.5 = 22.5
22.5 ÷ 2 = 11.25
Answer: Bridget takes 11.25 minutes to row 1 kilometer in still water.