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notka56 [123]
3 years ago
5

Heyy can you please help me posted picture of question

Mathematics
1 answer:
vichka [17]3 years ago
7 0
We can use quadratic formula to determine the roots of the given quadratic equation.

The quadratic formula is:

x= \frac{-b+- \sqrt{ b^{2} -4ac} }{2a}

b = coefficient of x term = 4
a = coefficient of squared term = 1
c = constant term = 7

Using the values, we get:

x= \frac{-4+- \sqrt{16-4(1)(7)} }{2(1)} \\  \\ 
x=  \frac{-4+- \sqrt{-12} }{2}   \\  \\ 
x= \frac{-4+-2 \sqrt{-3} }{2} \\  \\ 
x= -2+- \sqrt{-3}

So, the correct answer to this question is option A
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Suppose that the sample standard deviation was s = 5.1. Compute a 98% confidence interval for μ, the mean time spent volunteerin
NISA [10]

Answer:

The 95% confidence interval would be given by (5.139;5.861)  

Step-by-step explanation:

1) Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

\bar X represent the sample mean for the sample  

\mu population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size  

2) Confidence interval

Assuming that \bar X =5.5 and the ranfom sample n=1086.

The confidence interval for the mean is given by the following formula:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}   (1)

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:

df=n-1=1086-1=1085

Since the Confidence is 0.98 or 98%, the value of \alpha=0.02 and \alpha/2 =0.01, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.01,1085)".And we see that t_{\alpha/2}=2.33

Now we have everything in order to replace into formula (1):

5.5-2.33\frac{5.1}{\sqrt{1086}}=5.139    

5.5+2.333\frac{5.1}{\sqrt{1086}}=5.861

So on this case the 95% confidence interval would be given by (5.139;5.861)    We are 98% confident that the mean time spent volunteering for the population of parents of school-aged children is between these two values.

5 0
3 years ago
I need help with this one
antiseptic1488 [7]

Answer:

-12

Step-by-step explanation:

3 0
3 years ago
how do you solve -2.8k-4.31=-15.79 or 1.9m-3=-12.31 or 2.1a+1.4=-14.245 or 3.8n-4.8=-21.9 ?
Effectus [21]
Consider posting each question separately, please.

Given   <span>-2.8k-4.31=-15.79 :

1) Isolate the "k" term on the left by adding 4.31 to both sides of this equation.
2) Simplify the right side.
3) Divide both sides by -2.8 and you'll have the answer:  k = ?</span>
5 0
3 years ago
My homework says name a 2 digit odd number that is prime. name a 2 digit odd number that is composite.
lidiya [134]
2 digit meaning that it has 2 numbers. For example, 66 is a two digit number.
Now, they also said it must be prime, meaning that its factors can only be 1 and itself. 
Also, it must be odd. 

Answer:  67

Now, do the same, except the number must be composite, as meaning that it has other factors. 

Answer:   21
5 0
3 years ago
Read 2 more answers
Which statements about quadrilateral WXYZ are true? Select three options.
Andrej [43]

Answer:

The slope ZW is 2/5.

The length of ZY is 29.

Quadrilateral WXYZ is a square.

Step-by-step explanation:

I took the test.

7 0
3 years ago
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