Can someone help me please

Someone please help! Here's the question: Twenty boys signed up for the school play. The number of girls who signed up was 195%

kipiarov [429]

20*1.95 =39 girls
26girls/39girls =0.667
0.667*100 = 66.67%

8 0

4 years ago

A simple random sample of size nequals10 is obtained from a population with muequals68 and sigmaequals15. (a) What must be true

valentina_108 [34]

Answer:

(a) The distribution of the sample mean ( $\bar x$ ) is N (68, 4.74²).

(b) The value of $P(\bar X$ is 0.7642.

(c) The value of $P(\bar X\geq 69.1)$ is 0.3670.

Step-by-step explanation:

A random sample of size n = 10 is selected from a population.

Let the population be made up of the random variable X.

The mean and standard deviation of X are:

$\mu=68\\\sigma=15$

(a)

According to the Central Limit Theorem if we have a population with mean μ and standard deviation σ and we take appropriately huge random samples (n ≥ 30) from the population with replacement, then the distribution of the sample mean will be approximately normally distributed.

Since the sample selected is not large, i.e. n = 10 < 30, for the distribution of the sample mean will be approximately normally distributed, the population from which the sample is selected must be normally distributed.

Then, the mean of the distribution of the sample mean is given by,

$\mu_{\bar x}=\mu=68$

And the standard deviation of the distribution of the sample mean is given by,

$\sigma_{\bar x}=\frac{\sigma}{\sqrt{n}}=\frac{15}{\sqrt{10}}=4.74$

Thus, the distribution of the sample mean ( $\bar x$ ) is N (68, 4.74²).

(b)

Compute the value of $P(\bar X$ as follows:

$P(\bar X$

$=P(Z$

*Use a z-table for the probability.

Thus, the value of $P(\bar X$ is 0.7642.

(c)

Compute the value of $P(\bar X\geq 69.1)$ as follows:

Apply continuity correction as follows:

$P(\bar X\geq 69.1)=P(\bar X> 69.1+0.5)$

$=P(\bar X>69.6)$

$=P(\frac{\bar X-\mu_{\bar x}}{\sigma_{\bar x}}>\frac{69.6-68}{4.74})$

$=P(Z>0.34)\\=1-P(Z$

Thus, the value of $P(\bar X\geq 69.1)$ is 0.3670.

7 0

4 years ago

Find the equation of the line through (8,−6) which is perpendicular to the line y=x3−7.

ycow [4]

Answer:

y = (-1/3)(x + 10)

Step-by-step explanation:

The slope of the new (perpendicular) line is the negative reciprocal of the slope of the given line, which appears to be 3. Thus, the perpendicular line has the slope -1/3.

Using the slope-intercept form y = mx + b, and substituting the givens, we obtain:

y = mx + b => -6 = (-1/3)(8) + b, or

-6 = -8/3 + b. We must solve for the y-intercept, b:

Multiplying all three terms by 3 removes the fraction:

-18 = -8 + 3b. Thus, -10 = 3b, and so b must be -10/3.

The desired equation is

y = (-1/3)x - 10/3, or

y = (-1/3)(x + 10)

8 0

3 years ago

At the beginning of the year, 40% of the students at the art club were boys. In the middle of the year, 25% of the girls left bu

borishaifa [10]

Answer:

hi looks good

Step-by-step explanation:

jjhjvjedkfac

8 0

4 years ago

Find an equation of the line parallel to x=5y-9 and passing through (2,-4). Express in standard form.

Anon25 [30]

Answer:

x - 5y = 22

Step-by-step explanation:

Step 1: rewrite the equation of the given line in to slope-intercept form by solving for y

x = 5y - 9

-5y = -x - 9 (subtract 5y and x from both sides)

y = x/5 + 9/5 (divide both side by -5)

Step 2: Our line is parallel to this line, so it has the same slope, but a different y-intercept, so set up the equation...

y = x/5 + b

We are given a point (x, y) of (2, -4), so plug that in and solve for b.

-4 = 2/5 + b

-4 - 2/5 = b (subtract 2/5 from both sides to isolate b)

-20/5 - 2/5 = b

-22/5 = b (simplify)

So the equation of our line is y = x/5 - 22/5

Step 3: Standard form is ax + by = c, where a is a positive integer

subtract x/5 from both sides...

-x/5 + y = - 22/5

multiply by -5 so x becomes a positive integer

x - 5y = 22

3 0

3 years ago