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3 years ago

ben has 3 times as many guppies as goldfish. If he has a total of 20 fish, how mauy guppies does he have

2 answers:

7 0

$x-the \ number \ of \ goldfishes \\ 3x-the \ number \ of \ guppy \ fishes \\\\ x+3x=20 \\\\ 4x=20 \\\\ \boxed{x=\frac{20}{4}=5 } \\\\ 3*5\to\boxed{15 \ guppy \ fishes}$

NISA [10]3 years ago

3 0

Let,
the number of guppies be x
the number of goldfish be y
Since, Ben has 3 times as many guppies as goldfish, we can write,
x = 3y.............................equation (1)
Also,
It is given that he as total of 20 fish. So, we can say that,
x + y = 20
3y + y= 20..........substituting value of x from equation (1)
4y = 20
Divide both sides by 4 to get y by itself,
y = 20 / 4
y = 5

Now,
x = 3y
x = 3 * 5
x = 15

Since, number of guppies is x, we can say that he has 15 guppies

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3 years ago

-6/20+150% Please help I need the answer quickly.

tia_tia [17]

Is this

-6 ÷ 20 + 150%

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3 years ago

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A tunnel is in the shape of a parabola. The maximum height is 31 m and it is 13 m wide at the base as shown below.

yan [13]

Using the given values from the problem and the illustration, three points are known which are (0,0), (6.5,-31), (-6.5,-31). The first step in solving this problem is to determine the equation of the parabola.
y = ax²
-31 = a(6.5)²
-31 = 42.25a
a = -31/42.25
a = -124/169

Therefore, the equation of the parabola is y = (-124/169)x². The value 4.5 is then substituted in the equation as x to get the answer which is 16.14 meters.

6 0

2 years ago

A prism, bases of which are equilateral triangles, circumscribes a sphere of radius 6. What is the volume of the prism?

koban [17]

Answer:

1296√3 cubic units

Step-by-step explanation:

The volume of the prism will be the product of its base area and its height. Since it circumscribes a sphere with diameter 12, that is the height of the prism.

The central cross section of the sphere is a circle of radius 6, and that will be the size of the incircle of the base. That is, the base will have an altitude of 3 times that incircle radius, and an edge length of 2√3 times that incircle radius. Hence the area of the triangular base is ...

B = (1/2)(6×2√3)(6×3) = 108√3 . . . . . square units

The volume of the prism is then ...

V = Bh = (108√3)(12) = 1296√3 . . . cubic units

_____

Comment on the geometry

The centroid of an equilateral triangle is also the incenter and the circumcenter. The distance of that center from any edge of the triangle is 1/3 the height of the triangle. So, for an inradius of 6, the triangle height is 3×6 = 18. The side length of an equilateral triangle is 2/√3 times the altitude, so is 12√3 units for this triangle.

6 0

3 years ago

It is a well-known fact that 50% of the general population are rascals (P(R) = 0.5) and 50% of the general population are not ra

aleksley [76]

Answer:

The answer is D. 0.75

Step-by-step explanation:

Let call R the event that a person is rascal, RC a person is not rascal, TH a person use top hat and NTH a person don’t use top hat.

From the information on the question we have 4 options with their respective probability:

1. A person could be rascal and use top Hat: this probability is calculate as the multiplication of the probability of be a rascal (0.5) and use a top hat (0.9), then:

P(R y TH)=0.5*0.9=0.45

2. A person could be rascal and don’t use top Hat: this probability is calculate as the multiplication of the probability of be a rascal (0.5) and not use a top hat (0.9), then:

P(R y NTH)=0.5*0.1=0.05

3. A person could be not rascal and use top Hat: this probability is calculate as the multiplication of the probability of not be a rascal (0.5) and use a top hat (0.3), then:

P(RC y TH)=0.5*0.3=0.15

4. A person could be not rascal and not use top Hat: this probability is calculate as the multiplication of the probability of not be a rascal (0.5) and not use a top hat (0.7), then:

P(RC y NTH)=0.5*0.7=0.35

Then the probability that a person is a rascal given that he is wearing a top hat could be written and calculate as:

$P(R/TH)=\frac{P(R y TH)}{P(TH)}$

For calculate P(TH) we need to sum all the option in which TH is involve so:

P(TH) = P(R y TH)+ P(RC y TH)

P(TH)=0.45+0.15=0.6

Replacing values on the first equation we get:

$P(R/TH)=\frac{0.45}{0.6} =0.75$

So, the probability that a person is a rascal given that he is wearing a top hat is 0.75

5 0

3 years ago