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3 years ago

What percent of the first 20 natural numbers are prime numbers?

Mathematics

2 answers:

BARSIC [14]3 years ago

6 0

Answer: The required percentage is 40%.

Step-by-step explanation: We are given to find the percentage of the first 20 natural numbers that are prime.

We know that

first 20 natural numbers are 1, 2, 3, 4, . . . , 19, 20.

And, the prime numbers among them are 2, 3, 5, 7, 11, 13, 17 and 19.

So, if S be the sample space for the experiment and A be the event of selecting a prime number.

Then, we have

n(S) = 20 and n(A) = 8.

Therefore, the probability of event A is given by

$P(A)=\dfrac{n(A)}{n(S)}=\dfrac{8}{20}=\dfrac{2}{5}\times100\%=40\%.$

Thus, the required percentage is 40%.

Brilliant_brown [7]3 years ago

3 0

The primes are 2, 3, 5, 7, 11, 13, 17, 19. There are 8 of them, so they make up 40% of the numbers 1–20.

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Answer:

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Step-by-step explanation:

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3 years ago

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Two hiking groups made the purchases shown below. What is the cost of each item. GROUP 1: 6 muffins, 12 granola bars, Total=$26.

stepladder [879]

Answer:

Price of each muffin = $1.25

Price of each granola bar = $1.6

Step-by-step explanation:

Group 1:

6 muffins, 12 granola bars

Total money paid = $26.70

Group 2:

8 muffins, 15 granola bars,

Total money paid = $34.00

To find:

Price of each item?

Solution:

Let the price of one muffin = $ $x$

Let the price of one granola bar = $ $y$

As per group 1, the equation can be written as:

$6x+12y=26.70\\\Rightarrow x+2y=4.45 .... (1)$

As per group 2, the equation can be written as:

$8x+15y = 34$ .... (2)

Let us use elimination method to solve for $x$ and $y$ .

Multiplying equation (1) with 8 and subtracting (2) from it:

$16y-15y = 35.6 - 34\\\Rightarrow y = 1.6$

Using equation (1):

$x+3.2=4.45\\\Rightarrow x = 1.25$

Therefore, the answer is:

Price of each muffin = $1.6

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3 years ago

What is 20:50 (Equivalent Ratios)

Arturiano [62]

Answer: 20 : 50 (m1 = 1) 40 : 100 (m2 = 2) 60 : 150 (m3 = 3) 80 : 200 (m4 = 4) 100 : 250 (m5 = 5) . Bababoi

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Step-by-step explanation:

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AnnyKZ [126]

Answer

with

Step-by-step explanation:

Statement Reasons

1.∠1 ≅ 4 Given

2.∠1 = ∠2 Being Vertically opposite angles.

3.∠4 = ∠3 Being Vertically opposite angles.

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2 years ago

What is the area of the logo?

Ludmilka [50]

Answer:

$the \: area \: of \: the \: logo \: is \: {91cm}^{2}$

Step-by-step explanation:

To determine the area of the logo you have to calculate the area of the triangle and the square that comform it and then add the four areas.

Area of the square.

To calculate the area of the square you have to calculate the square of one of its sides, following the formula:

$a = {a}^{2}$

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The three triangles are equal, they have a base equal to the side of the square, i.e. with a length of 7cm, and their height is h=4cm.

To calculate the area of one triangle, you have to multiply its base by its height and divide by 2, following the formula:

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The area calculated the correspond to one triangle, since all triangles are congruent, you have to multiply the said area by 3 to determine the area of three figures:

$atriangles = 3a \\ atriangles = {42cm}^{2}$

Now that the area of all shape are calculated, you have to add them to determine the area of the logo:

$alogo = asquare + atriangle \\ alogo = 49 + 42 \\ alogo = {91cm}^{2}$

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3 years ago

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