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Varvara68 [4.7K]

3 years ago

10

A small amphitheater has 8 rows that have 42 seats in each row. If an act needs to keep the first row empty but has all the rest

of the seats sold, then what expression can be used to find the total attendance? 8 × 40 + 8 × 2 8 × 40 – 8 × 2 7 × 40 + 7 × 2 7 × 40 – 7 × 2

1 answer:

jok3333 [9.3K]3 years ago

4 0

Answer:

i dont know sorry

Step-by-step explanation:

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The Magic Dragon has 2013 heads. Leo the Brave is cutting off the Dragon's heads at a speed of 5 heads per minute. The Dragon's

aivan3 [116]

Answer: The answer is 1833 heads and 11 hours, 11 minutes.

Step-by-step explanation: Given that the Magic Dragon has 2013 heads. The brave Leo is cutting off the Dragon's heads at a speed of 5 heads per minute. But, the Dragon's heads are growing back at a speed of 2 heads per minute.

So, the number of heads of Dragon that are decreasing per minute = 3.

Therefore, after 1 hour, i.e., 60 minutes, The number of heads of the Dragon

= 2013 - 60 × 3 = 2013 - 180 = 1833 heads.

Now, the fight will last until all the heads of the Dragon are cut. Let the fight lasts for 'x' minutes, then

$2013-x\times 3=0\\\\\Rightarrow 3x=2013\\\\\Rightarrow x=\dfrac{2013}{3}=671.$

Hence the fight lasts for 671 minutes, i.e., 11 hours and 11 minutes.

Thus, the Dragon will have 1833 heads after 1 hour and the fight will last for 11 hour and 11 minutes.

3 0

3 years ago

What is Permutations and Combinations?

marissa [1.9K]

Answer:

See below

Step-by-step explanation:

Permutation is to select an object then arrange it and it cares about the orders while Combination is about only selecting an object without caring the orders.

Permutation can be expressed in math as:

$\displaystyle{_n P _r = \dfrac{n!}{(n-r)!} \ \ \ (n \geq r) }$

where n is a number of total object and r is a number of selected object to arrange. Hence. n cannot be less than r.

Now let's see an example of permutation, suppose we have letter A, B and C. I'd like to know how many ways these words can be arranged:

Since there are 3 letters total and 3 selected letters to arrange then:

$\displaystyle{_3 P _3 = \dfrac{3!}{(3-3)!}}\\\\\displaystyle{_3 P _3 = \dfrac{3 \times 2 \times 1}{0!}}\\\\\displaystyle{_3 P _3 = \dfrac{6}{1}}\\\\\displaystyle{_3 P _3 = 6}$

Therefore, there are 6 ways to arrange the letters - we can also demonstrate visually:

ABC - 1

ACB - 2

BAC - 3

BCA - 4

CAB - 5

CBA - 6

Notice that if you do visually, you'll get the same answer as the calculation of permutation!

----

Combination can be expressed mathematically as:

$\displaystyle{_n C _r = \dfrac{n!}{(n-r)!r!} = \dfrac{_n P _r}{r!} \ \ \ (n \geq r) }$

The difference between permutation and combination is that you only find how many ways you can select object in combination. Therefore, no arrange and doesn't care about order, just ways to select.

Suppose we have same 3 letters: A, B and C. I want to find how many ways I can select these 3 letters:

Since there are 3 letters total and 3 selected letters:

$\displaystyle{_3 C _3 = \dfrac{3!}{(3-3)!3!}}\\\\\displaystyle{_3 C _3 = \dfrac{3!}{0!3!}}\\\\\displaystyle{_3 C _3 = \dfrac{3!}{3!}}\\\\\displaystyle{_3 C _3 = 1}$

Hence, there is only one way to select 3 letters. This makes sense because if you have 3 letters then you can only select 3 letters only one way.

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2 years ago

Please help this is my last question

Serggg [28]

Answer:

The ratio to water to flour is 3:2

The chef will need 2 cups of water? - im not sure

The ratio to water to flour is 3:2.25 - im not sure

The chef will need 1.5 cups of flour.

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2 years ago

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Which of the following is the quotient of the rational expression (x-2/x+3) divided by (2/x)

zloy xaker [14]

Answer:

(x²-2x)/(2x+6)

Step-by-step explanation:

When you are asked to divide two fractions just do keep-change-flip. Keep the first fraction, change the ÷ to x and flip the second fraction upside down. So the problem becomes ((x-2)/(x+3)) times (x/2). Then just multiply numerators and multiply denominators.

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3 years ago

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velikii [3]

Answer would be the bottom answer

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2 years ago