My friend and I need help: a/4

How much does a sleeping bag cost? Let's say you want a sleeping bag that should keep you warm in temperatures from 20°F to 45°F

Ira Lisetskai [31]

Answer:

a) x = 80.40

s = 29.54

b) lower limit = 69.53

upper limit = 91.27

Step-by-step explanation:

The mean price is:

$\bar X=\frac{1}{n}\sum x_i=\frac{1}{20}(50+80+...+70)=\frac{1608}{20} =80.40$

The standard deviation is

$s=\sqrt{\frac{1}{n-1}\sum(x_i-\bar X)^2}=\sqrt{\frac{1}{19}[(50-80.4)^2+...+(70-80.4)^2]} \\\\s=\sqrt{\frac{15,471}{19} }=\sqrt{814.25} =29.54$

We have to calculate a 90% CI for the mean.

The z-value for a 90% confidence interval is z=1.645.

The margin of error is:

$E=z\cdot \sigma / \sqrt{n}=1.645*29.54/\sqrt{20}=48.59/4.47=10.87$

The 90% CI is

$\bar X-z\sigma/\sqrt{n} \leq \mu \leq \bar X-z\sigma/\sqrt{n}\\\\80.40-10.87 \leq \mu \leq 80.40+10.87\\\\69.53\leq \mu \leq 91.27$

4 0

4 years ago

Write a linear equation in standard form for the line that goes through (4,4)and (8,3)

Alexus [3.1K]

The standard equation of a line has the form:

y=mx+b

Where m is the slope of the line and b is the intercept.

The only thing we need to determine the equation of a line is two points, in this case, we have the points (4,4) and (8,3). Then, from the first point we know that when x equals 4 y equals 4 and from the second point we know that when x equals 8 y equals 3, we can express this with the standard formula of a line, like this:

4=m*4+b and 3=8*m+b

subtraction the second expression from the second one, we get:

4-3=m*4+b-8*m-b, we can cancel b and then we have:

4-3=m*4-m*8, we can subtract 3 from 4 in the left side and 8*m from 4*m from the right side and then:

1= -4*m , we can divide both sides by -4 and then:

m= -1/4

Now that we know the value of the slope, we only need to specify the value of b, we can do this by replacing the value of m in the expression 4=m*4+b of the first point and then solve for b, like this;

4=m*4+b, m=-1/4, then:

4= 4*(-1/4)+b, then:

4= -1+b, then, adding -1 in both sides we have:

4+1=b, then:

b=5

And the standar form of the line would be:

y=(-1/4)*x+5

5 0

1 year ago

What is the sum of the measures of the exterior angles of this triangle

Sever21 [200]

Answer:

360°

Step-by-step explanation:

The sum of all the exterior angles of a triangle is equal to 360 degrees.

3 0

4 years ago

Read 2 more answers

4. A dog shelter recorded the number of dogs, d, in their care as well as the pounds of dog food, f, the dogs consumed in a day.

dem82 [27]

Independent variable doesn’t change, dependent variable has a value that depends on another,

7 0

3 years ago

A library has five copies of a certain textbook on reserve of which two copies (1 and 2) are hardcover books and the other three

Gre4nikov [31]

Answer and Step-by-step explanation:

(a) Since the student have to stop when he gets to w softcover book, then the sample space should always stop at either 3 or 4 or 5. If the students examines the books randomly and stops at a softcover book, here are the possible ways he could carry this out,

S = {3, 4, 5, 13, 14, 15, 23, 24, 25, 123, 124, 125, 213, 214, 215}

2. Since only one book is to be examined then the student must check only one softcover book and end the examining. To do this, either he examines just 3 or 4 or 5. Therefore,

A = {3, 4, 5}

3. We need to pick the possibilities from the sample space that shows that the examining ended at book 5. Therefore,

B = {5, 15, 25, 125, 215}

4. We need to pick possibilities from the sample space that shows that book 1 was not examined. Therefore,

C = {3, 4, 5, 23, 24, 25}

5 0

3 years ago

My friend and I need help: a/4 - 5/6 = 1/2