A public school in your city has 1710 girls among the 2970 students. What is the ratio of boys to girls in school

Consider random samples of size 58 drawn from population A with proportion 0.77 and random samples of size 70 drawn from populat

fredd [130]

Answer:

Step-by-step explanation:

a) The formula for determining the standard error of the distribution of differences in sample proportions is expressed as

Standard error = √{(p1 - p2)/[(p1(1 - p1)/n1) + p2(1 - p2)/n2}

where

p1 = sample proportion of population 1

p2 = sample proportion of population 2

n1 = number of samples in population 1,

n2 = number of samples in population 2,

From the information given

p1 = 0.77

1 - p1 = 1 - 0.77 = 0.23

n1 = 58

p2 = 0.67

1 - p2 = 1 - 0.67 = 0.33

n2 = 70

Standard error = √{(0.77 - 0.67)/[(0.77)(0.23)/58) + (0.67)(0.33)/70}

= √0.1/(0.0031 + 0.0032)

= √1/0.0063

= 12.6

the standard error of the distribution of differences in sample proportions is 12.6

b) the sample sizes are large enough for the Central Limit Theorem to apply because it is greater than 30

8 0

3 years ago

A study by Consumer Reports showed that 64% of supermarket shoppers believe supermarket brands to be as good as national name br

natima [27]

Answer:

Step-by-step explanation:

Given that:

A study is conducted and the study by Consumer Reports showed that 64% of supermarket shoppers believe supermarket brands to be as good as national name brands.

a)

Thus; we formulate the null and the alternative hypotheses as follows:

The proportion is ; $\frac{64}{100}$ = 0.64

Null hypothesis: ${H_0}:p = 0.64$

The Null hypothesis states that there is no evidence that “the percentage of supermarket shoppers believes that the supermarket ketchup is good as the national brand ketchup differ form 64%”.

Alternative hypothesis: ${H_a}:p \ne 0.64H$

The Alternative hypothesis states that there is evidence that “the percentage of supermarket shoppers believes that the supermarket ketchup is good as the national brand ketchup differ form 64%”.

b)

The proportion of the population = 0.64

The sample size n = 100

The number of shoppers = 52 stating that the supermarket brand was as good as the national brand

The sample proportion $\hat p = \frac{52}{100}$

$\hat p = 0.52$

The z - value is calculated by the formula:

$z = \dfrac{\hat p-p}{\frac{\sqrt{ p(1-p)}}{100 }}$

$z = \dfrac{0.52-0.64}{\frac{\sqrt{ 0.64(1-0.64)}}{100 }}$

$z = \dfrac{-0.12}{0.048 }}$

z = -2.50

Since z = -2.50

the p-value = 2P(Z ≤ -2.50)

p-value = 2 × 0.0062

The p-value = 0.0124

c)

At significance level, ∝ = 0.05 ; The p-value = 0.0124

According to the rejection rule, if p-value is less than 0.05 then we will reject null hypothesis at ∝ = 0.05

Hence, the p-value =0.0124 < ∝ (=0.05)

According to the reject rule; reject null hypothesis.

Conclusion: There is no evidence at all that the percentage of supermarket shoppers believes that the supermarket ketchup is good as the national brand ketchup differ form 64%.

d) we know that the significance level of ∝ = 0.05

The value ${z__{0.05}}$ is obtained as:

$P\left( {\left| Z \right| \le z} \right) = 0.05$

Now; to determine Z ; we locate the probability value of 0.05 form the table of standard normal distribution. Then we proceed to the left until the first column is reached and the value is 1.90. Also , we move upward until we reach the top and the value is 0.06. Now; the intersection of the row and column results the area to the left of z

This implies that : $P(Z \leq -1.96)=0.05$

The critical value for left tail is -1.96 and the critical value for right tail is 1.96.

Conclusion:

The critical value is -1.96 and the value of test statistic is - 2.50. Here, we can see that the value of test statistic is lesser than the critical value. Hence, we can be concluded that there is evidence that reject the null hypothesis.

Therefore, Yes, the national brand ketchup manufacturer is pleased with the conclusion.

5 0

3 years ago

7 squared minus y equals 6 then y equals

vova2212 [387]

Answer:

Y = 43

Step-by-step explanation:

7^2 - y = 6

49 - y = 6

subtract 49

-y = -43

divide by -1

y = 43

6 0

3 years ago

Running at their respective constant rates, Machine X takes 2 days longer to produce w widgets than Machine Y. At these rates, i

Doss [256]

C. Hope this helps :)

5 0

3 years ago

A cylindrical piece of iron pipe is shown below. The wall of the pipe is 0.75 inch thick, and the pipe is open at both ends:

Gnesinka [82]

Answer:

(A)398 cubic inches

Step-by-step explanation:

Given a cylindrical piece of iron pipe with the following dimensions:

Height = 12 inches
Diameter = 8 inches

Therefore: External radius =4 Inches

Since the wall of the pipe is 0.75 inch thick,

Internal Radius =4-0.75 =3.25 Inches

Volume of a Cylinder = $\pi r^2 h$

Inside Volume of the Pipe

$= \pi*3.25^2*12\\=398$ cubic inches$

The correct option is A.

6 0

3 years ago