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1 year ago

Why wont anyone give me just the answers when i need them?

Mathematics

2 answers:

lina2011 [118]1 year ago

6 0

Answer:

id.k maybe because people are busy ,

i think the same as you.

Step-by-step explanation:

Anna71 [15]1 year ago

5 0

But where is the question please

You might be interested in

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.8. (Round your ans

Alenkinab [10]

Answer:

a) 0.011 = 1.1% probability that the sample mean hardness for a random sample of 17 pins is at least 51

b) 0.0001 = 0.1% probability that the sample mean hardness for a random sample of 45 pins is at least 51

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem, we have that:

$\mu = 50, \sigma = 1.8$

(a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 17 pins is at least 51?

Here $n = 17, s = \frac{1.8}{\sqrt{17}} = 0.4366$

This probability is 1 subtracted by the pvalue of Z when X = 51. So

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{51 - 50}{0.4366}$

$Z = 2.29$

$Z = 2.29$ has a pvalue of 0.9890

1 - 0.989 = 0.011

0.011 = 1.1% probability that the sample mean hardness for a random sample of 17 pins is at least 51

(b) What is the (approximate) probability that the sample mean hardness for a random sample of 45 pins is at least 51?

Here $n = 17, s = \frac{1.8}{\sqrt{45}} = 0.2683$

$Z = \frac{X - \mu}{s}$

$Z = \frac{51 - 50}{0.0.2683}$

$Z = 3.73$

$Z = 3.73$ has a pvalue of 0.9999

1 - 0.9999 = 0.0001

0.0001 = 0.1% probability that the sample mean hardness for a random sample of 45 pins is at least 51

8 0

3 years ago

Equations with parentheses may require the use of the distributive property to be solve

Mamont248 [21]

If this is a T/F question, then your answer is True .-.

8 0

2 years ago

A sporting goods store sells right-handed and left-handed baseball gloves. In one month, 12 gloves were sold for a total revenue

stepladder [879]

Answer:

$9$ right-handed gloves and $3$ left-handed gloves were sold.

Step-by-step explanation:

Given: In one month, $12$ gloves were sold for a total revenue of $\$561$ .

right-handed gloves cost $\$45$ and left-handed gloves cost $\$52$ .

To find: How much of each type of gloves did they sell?

Solution: Let they sell $x$ right-handed gloves, and $y$ left-handed gloves.

Now, cost of each right-handed gloves $=\$45$

cost of each left-handed gloves $=\$52$

Total revenue $=\$561$

So, we get

$45x+52y=561\:\:\:...(i)$

Also, in a month $12$ gloves were sold.

So, we get

$x+y=12\:\:\:...(ii)$

Now, from $(ii)$ we get, $x=12-y$ .

Putting $x=12-y$ in equation $(i)$ , we get

$45(12-y)+52y=561$

$\implies 540-45y+52y=561$

$\implies7y=561-540$

$\implies7y=21$

$\implies y=\frac{21}{7}$

$\implies y=3$

Now, putting $y=3$ in equation $(ii)$ , we get

$x+3=12$

$\implies x=12-3$

$\implies x=9$

Hence, $9$ right-handed gloves and $3$ left-handed gloves were sold.

7 0

2 years ago

Rewrite in polar form: x^2+y^2-2y=7

Alchen [17]

X²+y²-2y=7
using the formula that links Cartesian to Polar coordinates
x=rcosθ and y=r sin θ
substituting into our expression we get:
(r cos θ)²+(r sin θ)²-2rsinθ=7
expanding the brackets we obtain:
r²cos²θ+r²sin²θ=7+2rsinθ
r²(cos²θ+sin²θ)=7+2rsinθ
using trigonometric identity:
cos²θ+sin²θ=1
thus
r²=2rsinθ+7
Answer: r²=2rsinθ+7

8 0

2 years ago

Read 2 more answers

Segment AB has endpoints at A(-7,2) and b(9,-6). Point P lies on AB such that AP:BP=3:1

bekas [8.4K]

The coordinates of the point P which divides the line segment AB made by the points A(-7,2) and B(9,-6) is (x,y) = (5,-4)

<h3>What is the coordinate of the point which divides a line segment in a specified ratio?</h3>

Suppose that there is a line segment $\overline{AB}$ such that a point P(x,y) lying on that line segment $\overline{AB}$ divides the line segment $\overline{AB}$ in m:n, then, the coordinates of the point P is given by:

$(x,y) = \left( \dfrac{mx_2 + nx_1}{m+n} , \dfrac{my_2 + ny_1}{m+n} \right)$

where we have:

the coordinate of A is $(x_1, y_1)$
and the coordinate of B is $(x_2, y_2)$

We're given that:

Coordinate of A is $(x_1, y_1)$ = (-7,2)
Coordinate of B is $(x_2, y_2)$ = (9.-6)
The point P lies on AB such that AP:BP=3:1 (so m = 3, and n = 1)

Let the coordinate of P be (x,y), then we get the values of x and y as:

$(x,y) = \left( \dfrac{mx_2 + nx_1}{m+n} , \dfrac{my_2 + ny_1}{m+n} \right)\\\\(x,y) = \left( \dfrac{3(9) + 1(-7)}{3+1} , \dfrac{3(-6) + 1(2)}{3+1} \right)\\\\(x,y) = \left( \dfrac{20}{4} , \dfrac{-16}{4} \right) = (5,-4)$

Thus, the coordinates of the point P which divides the line segment AB made by the points A(-7,2) and B(9,-6) is (x,y) = (5,-4)

Learn more about a point dividing a line segment in a ratio here:

brainly.com/question/14186383

#SPJ1

4 0

2 years ago