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hjlf
3 years ago
12

A mixture of pulverized fuel ash and Portland cement to be used for grouting should have a compression strength of more than 130

0 KN/m^2. The mixture will not be used unless experimental evidence indicates conclusively that the strength specification has been met. Suppose compressive strength for specimens of this mixture is normally distributed with \sigma =60. Let \mu denote the true average compressive strength.What are the appropriate null and alternative hypothesis?
Mathematics
1 answer:
nekit [7.7K]3 years ago
7 0

Answer:

The null hypothesis is: u >= 1300 KN/m^2

And the alternative hypothesis is:

u < 1300 KN/m^2.

Step-by-step explanation:

The null hypothesis describes hat there is no difference or assiciation between variables of a specific population or that it is a particular average value while the alternative hypothesis states otherwise.

In this case study, the null hypothesis is: u >= 1300 KN/m^2

And the alternative hypothesis is:

u < 1300 KN/m^2.

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2 A and B please with explanation! BIG POINTS please explain
dedylja [7]

Answer:

see explanation

Step-by-step explanation:

Using the ratio equality for circles

\frac{arc}{C} = \frac{angleatcentre}{360}

(a)

Note the angle at the centre of the shaded arc is 360° - 90° = 270°, thus

\frac{45}{C} = \frac{270}{360} = \frac{3}{4} ( cross- multiply )

3C = 180 ( divide both sides by 3 )

C = 60 mm

(b)

Note the angle at the centre of the shaded arc is 360° - 135° = 225°, thus

\frac{3.3}{C} = \frac{225}{360} ( cross- multiply )

225C = 1188 ( divide both sides by 225 )

C = 5.28 cm

8 0
3 years ago
Simplify <br> 3(x - 6) - 4(x + 3).<br> A)-x - 30<br> B)-x - 9<br> C)-x - 6 <br> D)-x - 30
morpeh [17]

Answer:

-x-30

Step-by-step explanation:

<em>first you need to </em><em>distribute</em><em>:</em>

<em>3(x)+3(-6) -4(x)+ (-4)(3)</em>

<em>Then you </em><em>multiply:</em>

<em>3x+(-18)-4x+(-7)</em>

<em>then you </em><em>combine like terms:</em>

<em>3x-4x= -1x </em>

<em>-18+(-7)= -25</em>

<em>simplified:</em>

<u><em>-1x-30</em></u>

3 0
3 years ago
Read 2 more answers
Which expression is equivalent to the area of square A, in square inches?
Setler [38]

Answer:

length of 1 side of A, using the Pyth. Thm. and the dimensions of the other two squares: (side of A)^2 = (10 in)^2 + (24 in)^2. Then:

(side of A)^2 = 100+ 576 in^2 = 676 in^2.

Here I have not bothered to solve for the length of the side of A, since we want the area of square A. But if you do want the side length, find it: sqrt(676) = 26 in. Then the area of A is (26 in)^2 = 676 in^2.

Then the area of square A is (26 in)^2 =

Read more on Brainly.com - brainly.com/question/10676137#readmore

Step-by-step explanation:

8 0
3 years ago
One week the music store sold 2 trumpets, 3 clarinets, and 5 violins for $1,240. The next week, they sold 3 trumpets, 1 clarinet
garik1379 [7]

Answer:

Cost of Trumpets: $174

Cost of Clarinets: $149

Cost of Violins: $89

Step-by-step explanation:

Got it correct

4 0
3 years ago
You are planning a survey of starting salaries for recent computer science majors. In a recent survey by the National Associatio
nydimaria [60]

Answer:

A sample size of 554 is needed.

Step-by-step explanation:

We have that to find our \alpha level, that is the subtraction of 1 by the confidence interval divided by 2. So:

\alpha = \frac{1 - 0.95}{2} = 0.025

Now, we have to find z in the Ztable as such z has a pvalue of 1 - \alpha.

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Now, find the margin of error M as such

M = z\frac{\sigma}{\sqrt{n}}

In which \sigma is the standard deviation of the population and n is the size of the sample.

Standard deviation is known to be $12,000

This means that \sigma = 12000

What sample size do you need to have a margin of error equal to $1000, with 95% confidence?

This is n for which M = 1000. So

M = z\frac{\sigma}{\sqrt{n}}

1000 = 1.96\frac{12000}{\sqrt{n}}

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Dividing both sides by 1000:

\sqrt{n} = 1.96*12

(\sqrt{n})^2 = (1.96*12)^2

n = 553.2

Rounding up:

A sample size of 554 is needed.

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