A person swims 11 miles downstream in the same time they can swim 7 miles up stream. The speed of the current is 4 miles per hour. These situations can be represented by the equations
Downstream: t=11/s+4 Upstream:t=7/s-4,
where t stands for time and s is the speed of the swimmer. What is the speed of the swimmer swimming in still water?

s = 18 mph

Step-by-step explanation:

At downstream, time is; t = 11/(s+ 4)

At upstream, time is; t = 7/(s - 4)

Since they both are passed in the same time, then ;

11/(s+ 4) = 7/(s - 4)

Cross Multiply to get;

11(s - 4) = 7(s + 4)

11s - 44 = 7s + 28

11s - 7s = 44 + 28

4s = 72

s = 72/4

s = 18

rectangular prism would best match the box of cards

percentage - 25%

probability - 0.25

we know,

total amount of students in class = 20

total boys = 10

total girls = 10

no of girls who wear glasses = 10/2 = 5

probability of choosing a girl with glasses is =

number of girls wearing glasses/total number of students in the class = 5/20

thus, percentage of selecting a girl wearing glasses will be

= 5/20 × 100

= 5 × 5

25%

therefore,

probability will be 0.25

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