All categories

2 years ago

If x is a normal random variable with a standard deviation of 10, then 3x has a standard deviation equal to:

1 answer:

4 0

Standard deviation(σ $_{x}$ ) = √V(X) = 10
Therefore, variance of X. V(X) = 10² = 100

Variance of aX is given by,
V(aX) = a²V(X)

Therefore, variance of 3X will be,
V(3X) = 3²V(X) = 9(100) = 900

Therefore, standard deviation of 3X is,

σ $_{3x}$ = √V(3X) = √900 = 30

You might be interested in

Every day, a lecture may be canceled due to inclement weather with probability 0.05. Class cancelations on different days are in

andrezito [222]

<h3>(a)Probability of cancelling at least 4 classes is 0.0055.</h3><h3>(b)Probability of 10th class is third class that gets cancelled = 0.0031</h3>

Step-by-step explanation:

Here, the question is<u> incomplete</u>.

Every day, a lecture may be canceled due to inclement weather with probability 0.05. Class cancellations on different days are independent.

(a) There are 15 classes left this semester. Compute the probability that at least 4 of them get canceled.

(b) Compute the probability that the tenth class this semester is the third class that gets canceled.

Now, here:

The probability of cancelling each class = 0.05

Now, probability of cancelling at least 4 classes

= 1 - P(Cancelling at max 3 classes)

= 1 - P(0 ≤ x ≤ 3) = 1 - Binomial (15,0.05,3)

= 0.0055

Hence, probability of cancelling at least 4 classes is 0.0055.

(b) As given, 10th class is third class that gets cancelled.

So, the first and second classes that get cancelled in between 1 - 9.

P(2 class cancelled in 1st 9) = Binomial (15,0.05,3) = 0.0629

Also, as given P(10th class cancelled) = 0.05

⇒ P(10th class is third class that gets cancelled ) = 0.0629 x 0.05 = 0.0031

5 0

2 years ago

Isa and Jack have part-time jobs.

enot [183]

By process of elimination and plugging in the math we can say that Jack earns 8.25 an hour by multiplying 2*8.25=16.50. Isa must then earn 9.50, therefore she earns a greater hourly pay then Jack as a result

3 0

2 years ago

Steve likes to entertain friends at parties with "wire tricks." Suppose he takes a piece of wire 60 inches long and cuts it into

Alex_Xolod [135]

Answer:

a) the length of the wire for the circle = $(\frac{60\pi }{\pi+4}) in$

b)the length of the wire for the square = $(\frac{240}{\pi+4}) in$

c) the smallest possible area = 126.02 in² into two decimal places

Step-by-step explanation:

If one piece of wire for the square is y; and another piece of wire for circle is (60-y).

Then; we can say; let the side of the square be b

so 4(b)=y

b= $\frac{y}{4}$

Area of the square which is L² can now be said to be;

$A_S=(\frac{y}{4})^2 = \frac{y^2}{16}$

On the otherhand; let the radius (r) of the circle be;

2πr = 60-y

$r = \frac{60-y}{2\pi }$

Area of the circle which is πr² can now be;

$A_C= \pi (\frac{60-y}{2\pi } )^2$

$=( \frac{60-y}{4\pi } )^2$

Total Area (A);

A = $A_S+A_C$

= $\frac{y^2}{16} +(\frac{60-y}{4\pi } )^2$

For the smallest possible area; $\frac{dA}{dy}=0$

∴ $\frac{2y}{16}+\frac{2(60-y)(-1)}{4\pi}=0$

If we divide through with (2) and each entity move to the opposite side; we have:

$\frac{y}{18}=\frac{(60-y)}{2\pi}$

By cross multiplying; we have:

2πy = 480 - 8y

collect like terms

(2π + 8) y = 480

which can be reduced to (π + 4)y = 240 by dividing through with 2

$y= \frac{240}{\pi+4}$

∴ since $y= \frac{240}{\pi+4}$ , we can determine for the length of the circle ;

60-y can now be;

= $60-\frac{240}{\pi+4}$

= $\frac{(\pi+4)*60-240}{\pi+40}$

= $\frac{60\pi+240-240}{\pi+4}$

= $(\frac{60\pi}{\pi+4})in$

also, the length of wire for the square (y) ; $y= (\frac{240}{\pi+4})in$

The smallest possible area (A) = $\frac{1}{16} (\frac{240}{\pi+4})^2+(\frac{60\pi}{\pi+y})^2(\frac{1}{4\pi})$

= 126.0223095 in²

≅ 126.02 in² ( to two decimal places)

4 0

2 years ago

Which data set is least Likely to resemble a normal distribution?<br> Look at picture

kicyunya [14]

Answer: B) The heights of girls who live on a certain street in the city of Buffalo

Every answer choice starts with "the heights of all 14-year-old girls who", so we can ignore that part. Choice A describes the largest population while choice B describes the smallest population. In other words, choice A is very general and broad, while choice B is very specific and narrow. The more specific you get and the smaller the population is, the less likely its going to be normally distributed.

4 0

2 years ago

Juan walks a circular path with a radius of 280 yards at the local park. How far does she walk? Use 3.14 for pi.

belka [17]

Answer: Juan walks 246,176 yards around the circular path.

To find the distance around the circular path, we are looking for the circumference. The formula for the circumference is: C = pi(r^2).

Simply plug in the radius and evaluate the expression.

C = 3.14(280^2)
C = 3.14(78400)
C = 246,176 yd

4 0

2 years ago