Respuesta :
Answer:
6.11 km/hr
Step-by-step explanation:
We will use the distance equation: [tex]D=rt[/tex]
Where D is distance (in km), r is the speed/rate (in km/hr), and t is the time taken (in hours)
- The rate going downstream is with the current, so rate is r+c
- The rate going upstream is against the current, so rate is r-c
where c is current rate (river flow rate)
kelli swam upstream for some distance in one hour:
We can write [tex]d=(r-c)(1)\\d=r-c[/tex]
she then swam downstream for the same distance in only 6 minutes:
* note 6 minutes in hours is [tex]\frac{6}{60}=\frac{1}{10}[/tex]hr
We can write [tex]d=(r+c)(\frac{1}{10})\\d=\frac{1}{10}r+\frac{1}{10}c[/tex]
Since the river flows at 5km/hr, c is 5 and total distance is equal, so we can equate the distance and solve for r:
[tex]r-c=\frac{1}{10}r+\frac{1}{10}c\\r-5=\frac{1}{10}r+\frac{1}{10}(5)\\r-\frac{1}{10}r=\frac{1}{10}(5)+5\\\frac{9}{10}r=\frac{1}{2}+5\\\frac{9}{10}r=\frac{11}{2}\\r=\frac{\frac{11}{2}}{\frac{9}{10}}\\r=\frac{11}{2}*\frac{10}{9}=\frac{110}{18}=6\frac{1}{9}[/tex]
In decimal, 6.11 km/hr. This is Kelli's speed in still water.
Answer:
C, A, B, 6.11
Step-by-step explanation:
A. Kelli's swimming speed in still water
B. 1 (x- 5)
C. 0.1 (x+ 5)
D. 6.11 km/hr
