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tekilochka [14]
3 years ago
11

A circular swimming pool is 21 feet in diameter. What is the circumstances of the swimming pool?

Mathematics
1 answer:
Reptile [31]3 years ago
4 0
Hello there!


21 * 3.14 = 65.94


Thus,

The circumstances of the swimming pool is 65.94
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A man travels 20 km by car from Town P to Town Q at an average speed of x km/h. He finds that the time of the journey would be s
yuradex [85]

Answer:

x = 20.

Step-by-step explanation:

First, you should remember the relation:

Distance = Speed*Time.

First, we know that a man travels a distance of 20km at a speed of x km/h, in a time T.

We can write this as:

20km = (x km/h)*T

We know that the time is shortened by 12 minutes if the speed is increased by 5km/h

Rewriting these 12 minutes in hours (remember that 60min = 1 hour)

12 min = (12/60) hours = 0.2 hours

Then from this, he can travel the same distance of 20km in a time T minus 0.2 hours if the speed is increased by 5 km/h

We can write this as:

20km = (x + 5 km/h)*(T - 0.2 h)

Then we have a system of two equations, and we want to find the value of x:

20km = (x km/h)*T

20km = (x + 5 km/h)*(T - 0.2 h)

First, we should isolate the variable T in one of the equations, if we isolate it in the first one, we will get:

20km/(x km/h) = T

Replacing that in the other equation we get:

20km = (x + 5 km/h)*(T - 0.2 h)

20km = (x + 5 km/h)*( 20km/(x km/h) - 0.2 h)

Now we can solve this for x.

Removing the units (that we know that are correct) so the math is easier to read, we get:

20 = (x + 5)*(20/x - 0.2)

We only want to solve this for x.

20 = x*20/x - x*0.2 + 5*20/x - 5*0.2

20 = 20 - 0.2*x + 100/x - 1

subtracting 20 in both sides we get:

20 - 20 = 20 - 0.2*x + 100/x - 1 - 20

0 = -0.2*x + 100/x - 1

If we multiply both sides by x we get:

0 = -0.2*x^2 + 100 - x

-0.2*x^2 - x + 100 = 0

This is just a quadratic equation, we can solve it using the Bhaskara's equation, the solutions are:

x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4*(-0.2)*100} }{2*-0.2}  = \frac{1 \pm 9 }{-0.4}

Then the two solutions are:

x = (1 + 9)/-0.4 = -25

x = (1 - 9)/-0.4 = 20

As x is used to represent a speed, the negative solution does not make sense, so we should use the positive one.

x = 20

then the average speed initially is 20 km/h

3 0
2 years ago
Daniel wanted to know his approximate score on the final exam for his mathematics class. His professor hinted that his score was
frozen [14]

Answer: 101.69

Step-by-step explanation:

Formula we use to find the z-score :-

z=\dfrac{x-\mu}{\sigma}    (1)

Given : \mu=90

\sigma=7

Daniel's z score : z= 1.67

Let x be the raw score for Daniel's exam grade, then substitute the values of \mu,\ \sigma\ and \ x in (1), we get

1.67=\dfrac{x-90}{7}\\\\\Rightarrow\ x-90=7\times1.67\\\\\Rightarrow\ x=11.69+90=101.69

Hence, the raw score for Daniel's exam grade = 101.69

3 0
3 years ago
Does a heptogon have parallel lines please. help me
Tpy6a [65]
No they do not have parallel lines
4 0
3 years ago
Vanessa made 60 cupcakes for the party. 5% of the cupcakes were burnt.how many cupcakes did Vanessa burn
zaharov [31]
12 because u gotta divide 60 by 5%
5 0
3 years ago
Read 2 more answers
Pleas help me, this is confusing.
Dmitry_Shevchenko [17]
Ask your teacher or a family member
7 0
3 years ago
Read 2 more answers
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