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koban [17]
3 years ago
10

Can someone help me solve for a ?

Mathematics
2 answers:
abruzzese [7]3 years ago
8 0

Answer:

A is 7

Step-by-step explanation:

They want to know what value of a makes the determinant 39. Reverse the operations; to find determinants you take the main diagonal and subtract the minor diagonal from it. So, add 24 (6*4) to 39 = 63 then divide by 7 and your answer is 9.

VikaD [51]3 years ago
3 0

Answer:

a=9

Step-by-step explanation:

39+24=63

63/7=9=a

The matrix can be solved by a calculator too.

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uppose germination periods, in days, for grass seed are normally distributed and have a known population standard deviation of 2
natka813 [3]

Answer: 0.701

Step-by-step explanation:

Formula :  EBM =z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}} , where \alpha= significance level , \sigma = Population standard deviation, n= sample size.

As per given,  n= 22

\sigma = 2

Critical z- value for 90% confidence level : z_{\alpha/2}=1.645

Then,

 EBM =(1.645)\dfrac{2}{\sqrt{22}}\\\\=(1.645)\dfrac{2}{4.690416}\\\\\approx0.701

Hence ,  error bound (EBM) of the confidence interval with a 90% confidence level= ± 0.701

5 0
3 years ago
In a large population, 3% of the people are heroin users. A new drug test correctly identifies users 93% of the time and correct
kari74 [83]

Answer:

(a) The probability tree is shown below.

(b) The probability that a person who does not use heroin in this population tests positive is 0.10.

(c) The probability that a randomly chosen person from this population is a heroin user and tests positive is 0.0279.

(d) The probability that a randomly chosen person from this population tests positive is 0.1249.

(e) The probability that a person is heroin user given that he/she was tested positive is 0.2234.

Step-by-step explanation:

Denote the events as follows:

<em>X</em> = a person is a heroin user

<em>Y</em> = the test is correct.

Given:

P (X) = 0.03

P (Y|X) = 0.93

P (Y|X') = 0.99

(a)

The probability tree is shown below.

(b)

Compute the probability that a person who does not use heroin in this population tests positive as follows:

The event is denoted as (Y' | X').

Consider the tree diagram.

The value of P (Y' | X') is 0.10.

Thus, the probability that a person who does not use heroin in this population tests positive is 0.10.

(c)

Compute the probability that a randomly chosen person from this population is a heroin user and tests positive as follows:

P(X\cap Y)=P(Y|X)P(X)=0.93\times0.03=0.0279

Thus, the probability that a randomly chosen person from this population is a heroin user and tests positive is 0.0279.

(d)

Compute the probability that a randomly chosen person from this population tests positive as follows:

P (Positive) = P (Y|X)P(X) + P (Y'|X')P(X')

                  =(0.93\times0.03)+(0.10\times0.97)\\=0.1249

Thus, the probability that a randomly chosen person from this population tests positive is 0.1249.

(e)

Compute the probability that a person is heroin user given that he/she was tested positive as follows:

P(X|positive)=\frac{P(Y|X)P(X)}{P(positive)} =\frac{0.93\times0.03}{0.1249}= 0.2234

Thus, the probability that a person is heroin user given that he/she was tested positive is 0.2234.

6 0
3 years ago
4|n+8| = 56 <br><br>please help
Alchen [17]
To solve the absolute value equation you first need to get everything not in the absolute value bars to the other side of the equation.

Step 1) Divide by 4
|n+8| = 14

*Remember: when solving absolute value equations, you make what the expression (n+8) is equal to negative and positive. Not the other way around.

Step 2) Make two equations

n+8 = 14
n+8 = -14

Solve and you'll see that n= 6 and -22
3 0
3 years ago
Provide the first six terms of the following sequence:<br><br> t1=81 tn=1/3tn-1
Andrews [41]

We get tne n-th term with: tn=1/3tn-1

We know that the first term is t1=81, so 81=1/3t*1-1

81=1/3t-1

82=1/3t

82*3t=1

3t=1/82

t=1/82*3=1/246

The second term is: 1/

2*(1/246)*2)-1

We get the third term by replacing n with 3 and so on...

8 0
3 years ago
Read 2 more answers
Subtract. Write your answer as a fraction in simplest form.<br><br> −5/12 − 3/10=
OlgaM077 [116]

The answer would be -43/60 or -0.716 in decimal.

5 0
3 years ago
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