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3 years ago

Find the sum of the first six terms of the sequence for which a2=0.7 and a3=0.49.

Mathematics

2 answers:

alina1380 [7]3 years ago

8 0

A1 = 0.91
a6 = -0.14
sum = (0.91+-0.14) /2
sum = 2.31

Sloan [31]3 years ago

3 0

Answer: Sum of the first six terms is 2.31.

Step-by-step explanation:

Since we have given that

$a_2=0.7\\\\and\\\\a_3=0.49$

Since we know the formula for "Arithmetic Progression":

$a_2=a+d=0.7\implies a=0.7-d\\\\a_3=a+2d=0.49$

Now, solving the above two equations:

$a+2d=0.49\\\\0.7-d+2d=0.49\\\\0.7+d=0.49\\\\d=0.49-0.70\\\\d=-0.21$

So, when we put the value of d in the first equation, we get that

$a=0.7-d\\\\a=0.7+0.21\\\\a=0.91$

so, Sum of first six terms would be

$S_6=\dfrac{6}{2}(2\times 0.91+(6-1)\times -0.21)\\\\S_6=3(1.82+5\times -0.21)\\\\S_6=3(1.82-1.05)\\\\S_6=2.31$

Hence, Sum of the first six terms is 2.31.

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In a completely randomized experimental design, three brands of paper towels were tested for their ability to absorb water. Equa

arlik [135]

Answer:

Yes. At this significance level, there is evidence to support the claim that there is a difference in the ability of the brands to absorb water.

Step-by-step explanation:

The question is incomplete:

The significance level is 0.05.

The data is:

Brand X: 91, 100, 88, 89

Brand Y: 99, 96, 94, 99

Brand Z: 83, 88, 89, 76

We have to check if there is a significant difference between the absorbency rating of each brand.

Null hypothesis: all means are equal

$H_0:\mu_x=\mu_y=\mu_z$

Alternative hypothesis: the means are not equal

$H_a: \mu_x\neq\mu_y\neq\mu_z$

We have to apply a one-way ANOVA

We start by calculating the standard deviation for each brand:

$s_x^2=30,\,\,s_y^2=6,\,\,s_z^2=35.33$

Then, we calculate the mean standard error (MSE):

$MSE=(\sum s_i^2)/a=(30+6+35.33)/3=71.33/3=23.78$

Now, we calculate the mean square between (MSB), but we previously have to know the sample means and the mean of the sample means:

$M_x=92,\,\,M_y=97,\,\,M_z=84\\\\M=(92+97+84)/3=91$

The MSB is then:

$s^2=\dfrac{\sum(M_i-M)^2}{N-1}\\\\\\s^2=\dfrac{(92-91)^2+(97-91)^2+(84-91)^2}{3-1}\\\\\\s^2=\dfrac{1+36+49}{2}=\dfrac{86}{2}=43\\\\\\\\MSB=ns^2=4*43=172$

Now we calculate the F statistic as:

$F=MSB/MSE=172/23.78=7.23$

The degrees of freedom of the numerator are:

$dfn=a-1=3-1=2$

The degrees of freedom of the denominator are:

$dfd=N-a=3*4-3=12-3=9$

The P-value of F=7.23, dfn=2 and dfd=9 is:

$P-value=P(F>7.23)=0.01342$

As the P-value (0.013) is smaller than the significance level (0.05), the null hypothesis is rejected.

There is evidence to support the claim that there is a difference in the ability of the brands to absorb water.

3 0

3 years ago

I’m trying to get this math test done, can I please have some help?

Sati [7]

Answer: B

Step-by-step explanation:

If you use slope-intercept form, you can see that B uses the equation y = 5x - 4, and you can also see that it is linear since it is proportional. The only coordinate plane that has a nonlinear line is D.

5 0

2 years ago

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Anna [14]

If the slope is given then all is left is y-intercept which is equal to -3 which is also given in the question from the point (-4,-3), then your equation would be complete if you have these two so I think the answer is y=3/4x-3 and I’m really sorry if my answer is wrong but i tried my best and good luck!!

8 0

3 years ago

PLEASE HELP:

Lady bird [3.3K]

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Explanation:

(A)

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If a shape rotate 90 degree counterclockwise about the origin, then,

$(x,y)\rightarrow (-y,x)$