78 round off to the nearest ten

Two researchers conducted a study in which two groups of students were asked to answer 42 trivia questions from a board game. Th

Verizon [17]

Answer:

$(21.9-19.8) -1.966\sqrt{\frac{3.4^2}{200} +\frac{3.5^2}{200}}= 1.422$

$(21.9-19.8) -1.966 \sqrt{\frac{3.4^2}{200} +\frac{3.5^2}{200}}= 2.778$

And we are 95% confident that the true difference means are between $1.422 \leq \mu_1 -\mu_2 \leq 2.778$

Step-by-step explanation:

We know the following info:

$\bar X_1 = 21.9$ sample mean for group 1

$\bar X_2 = 19.8$ sample mean for group 2

$s_1 = 3.4$ sample standard deviation for group 1

$s_2 = 3.5$ sample standard deviation for group 2

$n_1 = 200$ sample size group 1

$n_2 = 200$ sample size group 2

We want to find a confidence interval for the difference of means and the correct formula to do this is:

$(\bar X_1 -\bar X_2) \pm t_{\alpha/2} \sqrt{\frac{s^2_1}{n_1} +\frac{s^2_2}{n_2}}$

Now we just need to find the critical value. The confidence level is 0.95 then the significance is $1-0.95 =0.05$ and $\alpha/2 =0.025$ . The degrees of freedom are given by:

$df= n_1 +n_2 -2= 200+200-2= 398$

The critical value for this case would be : $t_{\alpha/2}=1.966$

And replacing into the confidence interval formula we got:

$(21.9-19.8) -1.966\sqrt{\frac{3.4^2}{200} +\frac{3.5^2}{200}}= 1.422$

$(21.9-19.8) -1.966 \sqrt{\frac{3.4^2}{200} +\frac{3.5^2}{200}}= 2.778$

And we are 95% confident that the true difference means are between $1.422 \leq \mu_1 -\mu_2 \leq 2.778$

5 0

3 years ago

How much water should be added to 3 gallons of pure acid in order to obtain the 15% acid solution? HELP DUE BY TOMMOROW MORNING

Pani-rosa [81]

3 gallons of acid = 100% concentration acid
? (water+acid) gallons = 15 concentration acid

Note: Every gallon of water added reduces the percentage concentration of acid. Therefore, the relationship is inverse proportionality.

Solution:

Total number of gallons (water+acid) = (3*100)/15 = 20 gallons
Therefore, gallons of water = 20-3 = 17 gallons

5 0

3 years ago

A race car driving under the caution flag at 40 feet per second begins to accelerate at a constant rate after

vitfil [10]

Chelsea vs. Atlético Madrid, Champions League: Confirmed lineups; how to watch

7 0

3 years ago

Convert 9 cubic meters into cubic feet. Round your answer to the nearest whole number.

Aleksandr-060686 [28]

317.832

318

The exact answer is being written as a decimal. The rounded is answer will be 318. I hope this answers your question.

5 0

2 years ago

Read 2 more answers

The cost C in dollars of manufacturing x bicycles at a production plant is given by the function shown below.

Andreas93 [3]

Answer:

Minimum 100 bicycles
Minimum cost is 13500

Step-by-step explanation:

Given function:

C(x) = 3x^2- 600x + 43500

a.

Minimum cost is obtained at vertex.

Vertex is determined by formula x = -b/2a, in standard form of

f(x) = ax^2 + bx + c

Vertex of the given function is:

x = -(-600)/(2*3) = 100

b.

Cost at vertex is:

C(100) = 3*100^2 - 600*100 + 43500 = 13500

7 0

3 years ago