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zvonat [6]
4 years ago
8

if a given set has thirteen elements how many subsets have somewhere from four through eight elements

Mathematics
1 answer:
zmey [24]4 years ago
8 0
Of n elements, there are {}_nC_r=\dfrac{n!}{r!(n-r)!} ways of choosing any r elements. So the number of subsets that can be chosen from the set of 13 elements, each consisting of 4 to 8 elements, is

\displaystyle\sum_{r=4}^8{}_{13}C_r={}_{13}C_4+\cdots+{}_{13}C_8=6721

To compute the actual numbers, you have, for example,

{}_{13}C_4=\dfrac{13!}{4!(13-4)!}=\dfrac{13!}{4!9!}
=\dfrac{13\times12\times\cdots\times6\times5}{9\times8\times\cdots\times2\times1}
=\dfrac{13\times12\times11\times10}{4\times3\times2\times1}
=13\times11\times5
=715

so there are 715 ways of picking subsets of size 4. Compute the others similarly, then add them up.
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NEED HELP ASAP PLEASE HELP
morpeh [17]
From point A to C, which is the length of the entire line, it's 3x + 1.
AB = 2x + 4
BC = 10

This means that AB + BC = AC

All you have to do is plug in the equations.

(2x + 4) + (10) = (3x + 1)
2x + 14 = 3x + 1
2x + 13 = 3x
13 = x

Now plug in the value of x (13) into the AC equation (3x + 1).
AC = 3(13) + 1
AC = 39 + 1
AC = 40

The answer is:
a. 40
6 0
3 years ago
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Simplify to get the right answer
Musya8 [376]

The correct answer would be: 18+18i

5 0
4 years ago
Andrew is two years older than Beatrice, and Chris is three years younger than Beatrice.
In-s [12.5K]

Answer:

Beatrice's age is 34

Step-by-step explanation:

Beatruce = B

Andrew = B+2

Chris= B-3

B+(B+2) +(B-3 )= 67-B

3B-1 = 67-B

2B -1 = 67

2B= 68

B = 34

Beatrice is 34

Andrew is 36   (34+2)

Chris is 31 (34-3)

36+31 = 67

6 0
3 years ago
I will give you brianly look i want to know a+b=??
mr Goodwill [35]

Answer:

c

Step-by-step explanation:

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Rename 2/5 as a percent_______________________
loris [4]

It can be helpful to remember that "%" is just a shorthand way to write "/100" (divided by 100, or per 100, or per cent). ("Cent" is often used to refer to 100 or 1/100. A "cent" is 1/100 of a dollar, or 1/100 of an acre, for example. A <em>cent</em>ury is 100 years.)

Make the denominator of your fraction be 100. Multiply numerator and denominator by 20/20.

(2/5)×(20/20) = 40/100 = 40%

You can also get there via decimals.

... 2/5 = 0.4 = 0.40 (40 hundredths) = 40/100 (40 hundredths) = 40%

Or, you can multiply by 100%.

... (2/5)×(100%) = (200/5)% = 40%

7 0
3 years ago
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