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3 years ago

Is the number 191 a perfect square? explain.

Mathematics

2 answers:

Roman55 [17]3 years ago

7 0

It is not a perfect square, because 191’s square is not a whole number.

zloy xaker [14]3 years ago

5 0

It's can't be a perfect square!! because you can times 4 by something and get 191!!!

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A man starts walking north at 4 ft!s from a point . five minutes later a woman starts walking south at 5 ft!s from a point 500 f

damaskus [11]

Answer:

ds/dt = 6.98 ft/s

Step-by-step explanation:

- The speed of man due north Vm = 3 ft/s

- The speed of woman due south Vw = 4 ft/s

- Woman starts walking 5 mins later than man

Find:

At what rate are the people moving apart 15 min after the woman starts walking?

Solution:

- The total time for which the man is walking due north from P, is Tm:

Tm = 5 + 15 = 20 mins

- The total distance traveled by man in Tm mins is:

Dm = Tm*Vm

Dm = 20*60*3

Dm = 3,600 ft

- The total time for which the woman is walking due south from 500 ft due east from P, is Tw:

Tw = 15 = 15 mins

- The total distance traveled by man in Tw mins is:

Dw = Tw*Vw

Dw = 15*60*4

Dw = 3,600 ft

- The displacement between man and woman at any instance is (s) which can be related by pythagoras theorem as follows:

s^2 = (dm + dw)^2 + 500^2

Where, dm : Distance travelled by man at any time Tm

dw : Distance travelled by woman at any time Tw

- Differentiate s with respect to t:

2s*ds/dt = 2*(dm + dw)*(Vm + Vw)

s*ds/dt = (dm + dw)*(Vm + Vw)

ds/dt = [ (dm + dw)*(Vm + Vw) ] / s

- Evaluate the rate of separation of man and woman ds/dt by evaluating at instance Tm = 20 mins and Tw = 15 mins. We have:

ds/dt = [ (Dm + Dw)*(Vm + Vw) ] / sqrt ( (Dm + Dw)^2 + 500^2 )

- Plug in the values:

ds/dt = [ (3600 + 3600)*(3 + 4) ] / [sqrt ( (3600 + 3600)^2 + 500^2 )]

ds/dt = 6.98 ft/s

4 0

1 year ago

Answer the questions and provide an explanation (if needed).

s2008m [1.1K]

Answer:

1. 0 2. 130 3. -9.9

Step-by-step explanation:

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3 years ago

Suppose the weights of tight ends in a football league are normally distributed such that σ2=400. A sample of 11 tight ends was

AlladinOne [14]

Answer:

$217.636-1.96\frac{20}{\sqrt{11}}=205.817$

$217.636+1.96\frac{20}{\sqrt{11}}=229.455$

So on this case the 95% confidence interval would be given by (205.82;229.46)

Step-by-step explanation:

Assuming the following data: Weight 150 169 170 196 200 218 219 262 269 270 271

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)

$\sigma= \sqrt{400}= 20$ represent the population standard deviation

n=11 represent the sample size

Solution to the problem

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

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

In order to calculate the mean we can use the following formula:

$\bar X= \sum_{i=1}^n \frac{x_i}{n}$ (2)

The mean calculated for this case is $\bar X=217.636$

Since the Confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=NORM.INV(0.025,0,1)".And we see that $z_{\alpha/2}=1.96$