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A survey of 76 commercial airline flights of under 2 hours resulted in a sample average late time for a flight of 2.55 minutes.

nika2105 [10]

Answer:

The best point of estimate for the true mean is:

$\hat \mu = \bar X = 2.55$

$2.55-1.96\frac{12}{\sqrt{76}}=-0.148$

$2.55+1.96\frac{12}{\sqrt{76}}=5.248$

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

Step-by-step explanation:

Information given

$\bar X=2.55$ represent the sample mean for the late time for a flight

$\mu$ population mean

$\sigma=12$ represent the population deviation

n=76 represent the sample size

Confidence interval

The best point of estimate for the true mean is:

$\hat \mu = \bar X = 2.55$

The confidence interval for the true mean is given by:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

The Confidence level given is 0.95 or 95%, th significance would be $\alpha=0.05$ and $\alpha/2 =0.025$ . If we look in the normal distribution a quantile that accumulates 0.025 of the area on each tail we got $z_{\alpha/2}=1.96$

Replacing we got:

$2.55-1.96\frac{12}{\sqrt{76}}=-0.148$

$2.55+1.96\frac{12}{\sqrt{76}}=5.248$

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

7 0

3 years ago

You give tours on the Great Lakes and talk about points of interest. A lighthouse typically has 2 beacons that rotate together—b

tatiyna

Since the beacons rotate together, the angular speed is constant.

From the time you see the first beacon, you have to wait for the lighthouse to make 120°, i.e. 1/3 of a whole turn.

So, if T is the time it takes for the lighthouse to make a whole turn, the interval between the first and the second beacon is T/3.

The interval between the second and third beacon is the amount of time it takes to the lighthouse to make the remaining 2/3 of a turn, so that you'll see the first beacon again. So, this time is 2T/3

So, the ratio is

$\dfrac{2T}{3}\div\dfrac{T}{3}=\dfrac{2T}{3}\cdot\dfrac{3}{T}=2$

So, the time between the second and third beacon is twice as much the time between the first two.

5 0

3 years ago

Can you simplify 8/15+1/6

belka [17]

Answer:

Yes and the answer is 16/5

Step-by-step explanation:

Find the reciprocal of the divisor

Reciprocal of 1/6 : 6/1

Now, multiply it with the dividend

8/15 ÷ 1/6 = 8/15 × 6/1

And after that you get 48/15 but after reducing the fraction, the answer is 16/5. ( In mixed form, 3 1/5 )

I hope this helps and I am a middle school student answering this question.

5 0

2 years ago

Read 2 more answers

If f(x, y)=xy−x^2, what is the value of f(f(−2, 3), −4)? Explain your reasoning.

hjlf

$\bf f(x,y)=xy-x^2 \\\\[-0.35em] ~\dotfill\\\\ f(\stackrel{x}{-2},\stackrel{y}{3})=(-2)(3)-(-2)^2\implies f(-2,3)=-6-(4)\implies f(-2,3)=-10 \\\\[-0.35em] ~\dotfill\\\\ f(~~\underline{f(-2,3)},~~-4)\implies f(\stackrel{x}{\underline{-10}},\stackrel{y}{-4})=(-10)(-4)-(-10)^2 \\\\\\ f(-10,-4)=40-(100)\implies f(-10,-4)=-60$

3 0

3 years ago

Multiply. write the product in lowest terms. (2/3) (- 5/7)

Arturiano [62]

-10/21
2×-5=-10
3×7=21

8 0

3 years ago