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Alla [95]
2 years ago
8

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 hou

r.
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?
Mathematics
1 answer:
Natali [406]2 years ago
7 0

Answer:

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

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taurus [48]

Answer:

x^2 - 2x + 10, option B

Step-by-step explanation:

Complex numbers:

The most important relation that involves complex numbers is given by:

i^2 = -1

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

ax^{2} + bx + c, a\neq0.

This polynomial has roots x_{1}, x_{2} such that ax^{2} + bx + c = a(x - x_{1})*(x - x_{2}), given by the following formulas:

x_{1} = \frac{-b + \sqrt{\bigtriangleup}}{2*a}

x_{2} = \frac{-b - \sqrt{\bigtriangleup}}{2*a}

\bigtriangleup = b^{2} - 4ac

In this question:

The solutions are:

x_1 = 1 - 3i, x_2 = 1 + 3i

We have to find the polynomial. All option have a = 1. So

(x - (1 - 3i))(x - (1 + 3i)) = x^2 - x(1 + 3i) - x(1 - 3i) + (1 - 3i)(1 + 3i) = x^2 - x -3ix - x + 3ix + 1^2 - (3i^2) = x^2 - 2x + 1 - 9i^2 = x^2 - 2x + 1 - 9(-1) = x^2 - 2x + 10

The correct answer is given by option b.

6 0
3 years ago
If the diameter of the circle is 6 cm, find its circumference. [Use 3.14 for π.] A) 18.84 cm B) 25.12 cm C) 37.68 cm D) 50.24 cm
agasfer [191]
Circumference = π * d

π=3.14
diameter = 6

3.14 * 6 = 18.84.
The answer is A.

Hope this helped☺☺
7 0
3 years ago
Read 2 more answers
What percentage describes the probability of an impossible event
stich3 [128]
50% chance
Explanation
It’s possible... might might not happen
7 0
3 years ago
If the simple interest on $2,000 for 3 years is $300 then what is the interest rate?
Alona [7]

Answer:

100 dollars a year

Step-by-step explanation:

4 0
2 years ago
The Precision Scientific Instrument Company manufactures thermometers that are supposed to give readings of 0°C at the freezing
PSYCHO15rus [73]

Answer:

-1.53 , 1.53

Step-by-step explanation:

It is basically asking you to find the percentiles. so for the bottom 6.3% you would type into your calculator 2nd, VARS, invNorm, area: .063, mean: 0, and Standard Deviation: 1 which gives you -1.53.

for the upper 6.3% you have to take 1-.063=.937 to get the upper percentile. now type into your calculator 2nd, VARS, invNorm, area: .937, mean: 0, and Standard Deviation: 1 which gives you 1.53.


I hope I helped :D

6 0
1 year ago
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