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3 years ago

Here is a list of test scores: 86, 90, 93, 85, 79, 92 Find the mean ( average) of the test scores.

Mathematics

2 answers:

Mrac [35]3 years ago

5 0

Add them all up: 86+90+93+85+79+92=525
divide by 6 (because they provide 6 percentages): 525/6
mean=87.5

skelet666 [1.2K]3 years ago

4 0

86+90+93+85+79+92=525 divided by 6 is 87.5

The average is 87.5

(Add up all of the numbers and divide it by how many numbers there are)

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Three assembly lines are used to produce a certain component for an airliner. To examine the production rate, a random

Katyanochek1 [597]

Answer:

a) Null hypothesis: $\mu_A =\mu_B =\mu C$

Alternative hypothesis: $\mu_i \neq \mu_j, i,j=A,B,C$

$SS_{total}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x)^2 =20.5$

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2 =12.333$

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2 =8.16667$

And we have this property

$SST=SS_{between}+SS_{within}$

The degrees of freedom for the numerator on this case is given by $df_{num}=df_{within}=k-1=3-1=2$ where k =3 represent the number of groups.

The degrees of freedom for the denominator on this case is given by $df_{den}=df_{between}=N-K=3*6-3=15$ .

And the total degrees of freedom would be $df=N-1=3*6 -1 =15$

The mean squares between groups are given by:

$MS_{between}= \frac{SS_{between}}{k-1}= \frac{12.333}{2}=6.166$

And the mean squares within are:

$MS_{within}= \frac{SS_{within}}{N-k}= \frac{8.1667}{15}=0.544$

And the F statistic is given by:

$F = \frac{MS_{betw}}{MS_{with}}= \frac{6.166}{0.544}= 11.326$

And the p value is given by:

$p_v= P(F_{2,15} >11.326) = 0.00105$

So then since the p value is lower then the significance level we have enough evidence to reject the null hypothesis and we conclude that we have at least on mean different between the 3 groups.

b) $(\bar X_B -\bar X_C) \pm t_{\alpha/2} \sqrt{\frac{s^2_B}{n_B} +\frac{s^2_C}{n_C}}$

The degrees of freedom are given by:

$df = n_B +n_C -2= 6+6-2=10$

The confidence level is 99% so then $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ and the critical value would be: $t_{\alpha/2}=3.169$

The confidence interval would be given by:

$(43.333 -41.5) - 3.169 \sqrt{\frac{0.6667}{6} +\frac{0.7}{6}}= 0.321$

$(43.333 -41.5) + 3.169 \sqrt{\frac{0.6667}{6} +\frac{0.7}{6}}=3.345$

Step-by-step explanation:

Previous concepts

Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".

The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"

Part a

Null hypothesis: $\mu_A =\mu_B =\mu C$

Alternative hypothesis: $\mu_i \neq \mu_j, i,j=A,B,C$

If we assume that we have $3$ groups and on each group from $j=1,\dots,6$ we have $6$ individuals on each group we can define the following formulas of variation:

$SS_{total}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x)^2 =20.5$

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2 =12.333$

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2 =8.16667$

And we have this property

$SST=SS_{between}+SS_{within}$

The degrees of freedom for the numerator on this case is given by $df_{num}=df_{within}=k-1=3-1=2$ where k =3 represent the number of groups.

The degrees of freedom for the denominator on this case is given by $df_{den}=df_{between}=N-K=3*6-3=15$ .

And the total degrees of freedom would be $df=N-1=3*6 -1 =15$

The mean squares between groups are given by:

$MS_{between}= \frac{SS_{between}}{k-1}= \frac{12.333}{2}=6.166$

And the mean squares within are:

$MS_{within}= \frac{SS_{within}}{N-k}= \frac{8.1667}{15}=0.544$

And the F statistic is given by:

$F = \frac{MS_{betw}}{MS_{with}}= \frac{6.166}{0.544}= 11.326$

And the p value is given by:

$p_v= P(F_{2,15} >11.326) = 0.00105$

So then since the p value is lower then the significance level we have enough evidence to reject the null hypothesis and we conclude that we have at least on mean different between the 3 groups.

Part b

For this case the confidence interval for the difference woud be given by:

$(\bar X_B -\bar X_C) \pm t_{\alpha/2} \sqrt{\frac{s^2_B}{n_B} +\frac{s^2_C}{n_C}}$

The degrees of freedom are given by:

$df = n_B +n_C -2= 6+6-2=10$

The confidence level is 99% so then $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ and the critical value would be: $t_{\alpha/2}=3.169$

The confidence interval would be given by:

$(43.333 -41.5) - 3.169 \sqrt{\frac{0.6667}{6} +\frac{0.7}{6}}= 0.321$

$(43.333 -41.5) + 3.169 \sqrt{\frac{0.6667}{6} +\frac{0.7}{6}}=3.345$

7 0

3 years ago

The measures of three angles of a triangle are given by (8x - 5), (2x)º, and (3x – 10). What is the measure of the largest angle

zhannawk [14.2K]

Answer: 115°

Step-by-step explanation:

We should note that the sum of the angles that are in a triangle is equal to 180°, therefore we will add the angles given and equate them to 180°. This will be:

(8x - 5) + (2x) + (3x - 10) = 180

8x - 5 + 2x + 3x - 10 = 180

Collect like terms

8x + 2x + 3x = 180 + 5 + 10

13x = 195

x = 195/13

x = 15

The angles are:

8x - 5 = 8(15) - 5 = 120 - 5 = 115°

2x = 2(15) = 30°

3x - 10 = 3(15) - 10 = 45 - 10 = 35°

Therefore, the largest angle is 115°

3 0

2 years ago

What’s the answer and the work ?

Phoenix [80]

Answer:

2√14

Step-by-step explanation:

√56

√2^2 x 14

√2^2 √14

2√14

5 0

3 years ago

The amount of money that Li spends on a video game depends on how many game he purchases. if Li has at most $90 to spend on game

siniylev [52]

Answer:

Hence Domain set for function is {0,1,2,3,4}

Step-by-step explanation:

Given:

Total amount spend =90

22.5 $ each game cost

To Find:

What is domain for the function

Solution:

Now domain mean all possible value for input so that it gives real output as per condition mentioned

So Our condition is that li spends money on video game depends on how many game he purchases

so total money spent on game is output

i.e in order to get that much amount of games.

If he spends 22.5 $ for each game and Total amount spent is 90

So 90/22.5=4 Now amount of game he would purchase will be 4

i.e range for lil is 0 to 4 wiht 90 $ in hand

So Domain set will be ranging from{0,1,2,3,4}

7 0

3 years ago

Find the perimeter. Simplify your answer.

dimaraw [331]

Answer:

30y+14

Step-by-step explanation:

add the values of all the sides together: (5y+4) + (5y+4) + (10y+3) + (10y+3) = (5y + 5y + 10y + 10y) + (4 + 4 + 3 + 3)= 30y + 14

5 0

2 years ago