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Dovator [93]
3 years ago
9

Find S15 for the series -1 + -3 + -5 + -7 +...

Mathematics
1 answer:
Ber [7]3 years ago
8 0
Hello :
the sum is  arithmetic secquence of common -diff is :
(-7)-(-5) =(-5)-(-3) = (-3)-(-1) =-2 = d
  the first term is : a1 = -1
<span>the formula of the sum :  S= (n/2)(a1 +an)
n is number of term       an = a1+(n-1)d</span>
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Somebody please help me with this !!!
Damm [24]

Step-by-step explanation:

Case 1 :

3x + 2y = 6 \\ 4x + y = 2 \\ 3x = 6 - 2y \\ x =  \frac{6 - 2y}{3}  = \\ x = 2 -  \frac{2y}{3}  \\ 4(2 -  \frac{2y}{3} ) + y = 2 \\ 8 -  \frac{8y}{3}  + y = 2 \\  - 1.67y =  - 6 \\

y = 3.59 \\ x = 2 -  \frac{2y}{3}  \\x =  2 -  \frac{2 \times 3.59}{3}  \\  \\ x =  - 0.39

Case 2 :

3x + 2y = 6 \\ 4x  -  y = 2 \\ x = 2 -  \frac{2y}{3}  \\ 4(2 -  \frac{2y}{3} ) - y = 2 \\ 8 -  \frac{8y}{3}  - y = 2 \\   - 3.67y=  - 6 \\ y = 1.63

x = 2 -  \frac{2y}{3}  \\ x = 2 -  \frac{2 \times 1.63}{3}  \\ x = 2 - 1.087 \\ x = 0.913

7 0
3 years ago
A shipment of 12 microwave ovens contains 3 defective units. A vending company has ordered 4 of these units, and because all are
pishuonlain [190]
P(defective) = 3/12 = 1/4
P(good) = 1 - 1/4 = 3/4
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P(4\ good)=0.75^{4}=0.316
The probability that at least 2 units are good is given by:
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4 0
3 years ago
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Find the area of the triangle ? Square units
allochka39001 [22]

Answer:

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Step-by-step explanation:

9(0.5)(12)

54

8 0
3 years ago
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And buys a pencil for $0.45 draw and label coins. Ann could use to make $0.45
jekas [21]

Answer:

You could use one quarter and two dimes... that will equal $0.45

(I'm not sure what you are asking for)

4 0
3 years ago
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recent research indicated that about 20% of british children are deficient in vitamin d. suppose doctors test a group of element
blsea [12.9K]

If about 20% of British children are deficient in vitamin and doctors test a group of elementary school children, the probability that the first vitamin d-deficient child is the 8th one tested is 4.19% determined using geometric distribution formula.

In probability and statistics, geometric distribution refers to the probability that first success would occurs after n number of trials and is given by:

P(X)=q^(x-1)p

Where p is the probability of success and q is (1-p)

In this case,

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q= probability of children not deficient in vitamin= 0.8

Hence,

P(8)=0.8^(8-1)*0.2= 0.0419

Hence, the probability that 8th child is deficient is 4.19%

Learn more about geometric distribution:

brainly.com/question/14957440

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8 0
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