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lana66690 [7]
3 years ago
7

How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 95% confidence that

the sample mean is within 5 minutes of the population mean, and the population standard deviation is known to be 7 minutes.
Mathematics
1 answer:
lukranit [14]3 years ago
5 0

Answer: 25 computers will be selected

Step-by-step explanation:

Where: Z -value at 95% confidence = 1.96; SD = Standard deviation = 10 minutes; N = Sample size; Margin error = 4 minutesSubstituting;4 = 1.96*10/Sqrt (N)Sqrt (N) = (1.96*10)/4 = 4.9N = 4.9^2 = 24.01 ≈ 25

You might be interested in
There are 128 students going on a field trip to pan for gold. If they are going in vans that hold 7 students each, how many vans
Viefleur [7K]
128/7 is roughly 18.3 so you would need 19 vans. 18 of them would fit all 7 so you’d have 126 so the last van would fit 2 students meaning it won’t be full
6 0
3 years ago
What values of y satisfy this equation?<br><br> 3y - 14 = 16
TiliK225 [7]

Answer:

By making y alone

Step-by-step explanation:

3y-14=16

   +14  +14

3y=  30

divide 3 on both sides

y=10

Hope this helps!

6 0
4 years ago
You are constructing a cardboard box from a piece of cardboard with the dimensions 2 m by 4 m. You then cut equal-size squares f
postnew [5]

Answer:

Dimensions:

l =3,15 m

w=1,15 m

x= 0,42 m   (height)

V(max) = 1,52 m³

Step-by-step explanation:

The cardboard is L = 4 m   and   W = 2 m

Let call x the length of the square to cut in each corner, then, volume of open box is:

For the side L       is  L - 2*x               l =  4 - 2*x

For the side W      is  W - 2*x             w=  2 - 2*x

The height              is  x

Volume of the open box, as function of x is:

V(x) = ( 4 -2x) * ( 2 - 2x) *x    ⇒  V(x) = ( 8 - 8x -4x + 4x²) *x

V(x) = ( 8 -12x + 4x² )*x     V(x) = 8x - 12x² + 4x³

V(x) = 8x - 12x² + 4x³

Taking derivatives on both sides of the equation

V´(x) = 8 - 24x + 12x²

V´(x) = 0       8  - 24x + 12x² = 0     reordering    12x² - 24x + 8  = 0

or    3x² - 6x + 2 = 0

A second degree equation. Solving for x

x₁,₂  = ( 6 ± √36 - 24 ) /6

x₁,₂  = ( 6 ± 3.46) /6

x₁  =  6 + 3,46 /6     x₁  = 1.58  we dismiss such solution because 1,58 * 2 = 3,15 and is bigger than 2 one of the side of the cardboard

x₂  =( 6 - 3,46 ) / 6

x₂  = 0,42 m

Dimensions of the open box

l  = 4 - 2*x     l  = 4 - 0,85      l  =  3,15 m

w = 2 -2*x    w  = 2 - 0,85     w = 1,15 m

x = 0,42 m

V(max) =3,15*1,15*0,42

V(max) = 1,52 m³

8 0
3 years ago
Sunspots have been observed for many centuries. Records of sunspots from ancient Persian and Chinese astronomers go back thousan
Lunna [17]

Answer:

(a) Null Hypothesis, H_0 : \mu \leq 41  

    Alternate Hypothesis, H_A : \mu > 41

(b) The value of z test statistics is 1.08.

(c) We conclude that the mean sunspot activity during the Spanish colonial period was lesser than or equal to 41.

Step-by-step explanation:

We are given that in a random sample of 40 such periods from Spanish colonial times, the sample mean is x¯ = 47.0. Previous studies of sunspot activity during this period indicate that σ = 35.

It is thought that for thousands of years, the mean number of sunspots per 4-week period was about µ = 41.

Let \mu = <u><em>mean sunspot activity during the Spanish colonial period.</em></u>

(a) Null Hypothesis, H_0 : \mu \leq 41     {means that the mean sunspot activity during the Spanish colonial period was lesser than or equal to 41}

Alternate Hypothesis, H_A : \mu > 41     {means that the mean sunspot activity during the Spanish colonial period was higher than 41}

The test statistics that would be used here <u>One-sample z test statistics</u> as we know about the population standard deviation;

                            T.S. =  \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }  ~ N(0,1)

where, \bar X = sample mean = 47

            σ = population standard deviation = 35

            n = sample of periods from Spanish colonial times = 40

So, <em><u>the test statistics</u></em>  =  \frac{47-41}{\frac{35}{\sqrt{40} } }

                                      =  1.08

(b) The value of z test statistics is 1.08.

(c) <u>Now, the P-value of the test statistics is given by;</u>

                P-value = P(Z > 1.08) = 1 - P(Z < 1.08)

                              = 1 - 0.8599 = <u>0.1401</u>

Since, the P-value of the test statistics is higher than the level of significance as 0.1401 > 0.05, so we have insufficient evidence to reject our null hypothesis as it will not fall in the rejection region due to which <u>we fail to reject our null hypothesis</u>.

Therefore, we conclude that the mean sunspot activity during the Spanish colonial period was lesser than or equal to 41.

8 0
4 years ago
The legs of a isosceles triangle are 0.3 foot less then twice the base . The perimeter of the triangle is 4.9 feet .
kicyunya [14]
<h2>Greetings!</h2>

Answer:

The legs are 1.9 feet long

And the base is 1.1 feet long.

Step-by-step explanation:

Firstly, you need to find the value of x.

You need to add all the sides together:

2x - 0.3 + 2x - 0.3 + x

Simplified =

5x - 0.6

And this equals 4.9:

5x - 0.6 = 4.9

Next, you need to move the -0.6 over to the other side, making sure to make it a positive:

5x = 4.9 + 0.6

5x = 5.5

Now divide each side by 5:

\frac{5x}{5} = \frac{5.5}{5}

x = 1.1


As the image is unclear of what side you are finding the length of:

2x - 0.3 = 1.9 feet long

And the base is 1.1 feet long.


<h2>Hope this helps!</h2>
4 0
3 years ago
Read 2 more answers
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