Question

Sara can row downstream at 15 km/hr and upstream at 11 km/hr. Find her speed in still water.​

Answer 1

Answer:

Sara's speed in still water is 13km/hr.

Step-by-step explanation:

Let Sara's speed be x km/hr

Let the speed of the stream be y km/hr

Speed downstream = x + y

15 = x + y

15 - y = x------(1)

speed upstream = x-y

11 = x - y--------(2)

substitute the value of x in (1) into (2)

11 = 15 - y - y

11 - 15 = -2y

-4 = -2y

4/2 = y

2 = y--------(3)

substitute the value of y in (1)

15 - 2 = x

13 = x

Therefore Sara's speed in still water is 13km/hr.