Y = 2x – 1<br><br> Please help

madam [21]

5:5 (first box, pencils to pens)

7:3 (second box, coloured pencils to crayons)

The probability of picking a pen (1st box): 5/10

The probability of picking a crayon (2nd box): 3/10

Probability of picking both: 5/10*3/10 = 15/100

7 0

3 years ago

Read 2 more answers

The U.S. Center for Disease Control reports that the mean life expectancy was 47.6 years for whites born in 1900 and 33.0 years

inn [45]

Answer:

b. The null and alternative hypothesis are:

$H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2\neq 0$

c. Student's t distribution, as it is a two-sample test for the difference between means.

d. Test statistic t = 5.42.

P-value = 0

e. They appear to be significantly different, as the sample data gives strong evidence that the difference is greater than 0.

Step-by-step explanation:

This is a hypothesis test for the difference between populations means.

The claim is that the mean life spans in the county is significantly different for whites and nonwhites.

Then, the null and alternative hypothesis are:

$H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2\neq 0$

The significance level is 0.05.

The sample 1 (white), of size n1=124 has a mean of 45.3 and a standard deviation of 12.7.

The sample 2 (non-white), of size n2=82 has a mean of 34.1 and a standard deviation of 15.6.

The difference between sample means is Md=11.2.

$M_d=M_1-M_2=45.3-34.1=11.2$

The estimated standard error of the difference between means is computed using the formula:

$s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{12.7^2}{124}+\dfrac{15.6^2}{82}}\\\\\\s_{M_d}=\sqrt{1.301+2.968}=\sqrt{4.269}=2.066$

Then, we can calculate the t-statistic as:

$t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{11.2-0}{2.066}=\dfrac{11.2}{2.066}=5.42$

The degrees of freedom for this test are:

df=n_1+n_2-2=124+82-2=204

This test is a two-tailed test, with 204 degrees of freedom and t=5.42, so the P-value for this test is calculated as (using a t-table):

$\text{P-value}=2\cdot P(t>5.42)=0.0000002$

As the P-value (0.0000002) is smaller than the significance level (0.05), the effect is significant.

The null hypothesis is rejected.

There is enough evidence to support the claim that the mean life spans in the county is significantly different for whites and nonwhites.

4 0

3 years ago

The marketing department of a sports supply store wants to estimate the percentage of adults in the town who belong to a gym.

velikii [3]

A) If you only sample people in a sports supply store, your sample will be biased. People in a sports supply store are more likely to be people that belong to a gym.
B) While it does not have necessarily the same amount of bias as sampling people in the sports supply store, people that go to a park are generally more likely to be people that exercise or have a gym membership.
C) Taking a random sample of people in town is a good way to get a non-biased sample. They are not necessarily predisposed to answer your question one way or another.
D) For the same reason as choice A, this is a biased sample.

C is the best choice.

4 0

3 years ago

50 points. <br> Solve the following problems.

jeyben [28]

Answer:

x=10, y=12.

Step-by-step explanation:

You are making all sides of the triangle smaller by a scale factor of 2/3, because 9*2/3=6. For x, we can do 2/3*15, which equals 10. For y, we can do 2/3*18, equalling 12.

3 0

3 years ago

Read 2 more answers

Lin ran 2 3/4 miles in 2/5 of an hour. Noah ran 8 2/3 miles in 4/3 of an hour.

sveticcg [70]

(The second one)
Noah ran 8.67 miles in 1 hour and 20 minutes
If we convert the fraction to a decimal (for the miles part) we get 8.67 or 8 2/3 miles.

If 1/3 of an hour is 20 minutes, and an hour is 60 minutes, we add 20 4 times, which gets us to 80, which is 20 past an hour.

6 0

3 years ago

Y = 2x – 1 Please help