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Studentka2010 [4]
3 years ago
15

To obtain information on the corrosion-resistance properties of a certain type of steel conduit, 45 specimens are buried in soil

for a 2-year period. The maximum penetration (in mils) for each specimen is then measured, yielding a sample average penetration of x = 52.4 and a sample standard deviation of s = 4.7. The conduits were manufactured with the specification that true average penetration be at most 50 mils. They will be used unless it can be demonstrated conclusively that the specification has not been met. What would you conclude? (Use α = 0.05.) State the appropriate null and alternative hypotheses.
Mathematics
1 answer:
Fiesta28 [93]3 years ago
5 0

Answer:

The sample has not met the required specification.

Step-by-step explanation:

As the average of the sample suggests that the true average penetration of the sample could be greater than the 50 mils established, we formulate our hypothesis as follow

H_0: The true average penetration is 50 mils

H_a: The true average penetration is > 50 mils

Since we are trying to see if the true average is greater than 50, this is a right-tailed test.

If the <em>level of confidence</em> is α = 0.05 then the z_\alpha score against we are comparing with, is 1.64 (this is because the area under the normal curve N(0;1) to the right of 1.64 is 0.05)

The z-score associated with this test is

z=\frac{\bar x-\mu}{s/\sqrt{n}}

where

\bar x = <em>mean of the sample</em>

\mu = <em>average established by the specification</em>

s = <em>standard deviation of the sample</em>

n = <em>size of the sample</em>

Computing this value of z we get z = 3.42

Since z >z_\alpha we can conclude that the sample has not met the required specification.

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ki77a [65]
The distance between the points (d) is found using the Pythagorean theorem.

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   d² = 4² + 7²
   d² = 16 + 49
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The distance between the points is
   C  8.1


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You know that the distance must be longer than the longest leg (7) and must be shorter than the sum of the two legs (4+7=11). The only answer choice between 7 and 11 is 8.1.

8 0
3 years ago
(3 points)
Snezhnost [94]

Answer:

The exponential Function is 20+12h=200.

Farmer will have 200 sheep after <u>15 years</u>.

Step-by-step explanation:

Given:

Number of sheep bought = 20

Annual Rate of increase in sheep = 60%

We need to find that after how many years the farmer will have 200 sheep.

Let the number of years be 'h'

First we will find the Number of sheep increase in 1 year.

Number of sheep increase in 1 year is equal to Annual Rate of increase in sheep multiplied by Number of sheep bought and then divide by 100.

framing in equation form we get;

Number of sheep increase in 1 year = \frac{60}{100}\times20 = 12

Now we know that the number of years farmer will have 200 sheep can be calculated by Number of sheep bought plus Number of sheep increase in 1 year multiplied by number of years  is equal to 200.

Framing in equation form we get;

20+12h=200

The exponential Function is 20+12h=200.

Subtracting both side by 20 using subtraction property we get;

20+12h-20=200-20\\\\12h=180

Now Dividing both side by 12 using Division property we get;

\frac{12h}{12} = \frac{180}{12}\\\\h =15

Hence Farmer will have 200 sheep after <u>15 years</u>.

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3 years ago
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7 0
3 years ago
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Triangle Proofs Please help
oksian1 [2.3K]

Explanation:

There may be a more direct way to do this, but here's one way. We make no claim that the statements used here are on your menu of statements.

<u>Statement</u> . . . . <u>Reason</u>

2. ∆ADB, ∆ACB are isosceles . . . . definition of isosceles triangle

3. AD ≅ BD

and ∠CAE ≅ ∠CBE . . . . definition of isosceles triangle

4. ∠CAE = ∠CAD +∠DAE

and ∠CBE = ∠CBD +∠DBE . . . . angle addition postulate

5. ∠CAD +∠DAE ≅ ∠CBD +∠DBE . . . . substitution property of equality

6. ∠CAD +∠DAE ≅ ∠CBD +∠DAE . . . . substitution property of equality

7. ∠CAD ≅ ∠CBD . . . . subtraction property of equality

8. ∆CAD ≅ ∆CBD . . . . SAS congruence postulate

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4 0
2 years ago
When two six-sided dice are rolled, there are 36 possible outcomes. Find the probability that the sum is not 5.
zaharov [31]

Answer:

p(Not\ 5) = \frac{8}{9}

Step-by-step explanation:

Given:

Txo six-sided dice are rolled.

Total number of outcomes n(S) = 36

We need to find the probability that the sum is not equal to 5 p(Not 5).

Solution:

Using probability formula.

P(E)=\frac{n(E)}{n(S)}  ----------------(1)

Where:

n(E) is the number of outcomes favourable to E.

n(S) is the total number of equally likely outcomes.

The sum of two six-sided dice roll outcome is equal to 5 as.

Outcome as 5: {(1,4), (2,3), (3,2), (4,1)}

So, the total favourable events n(E) = 4

Now, we substitute n(E) and n(s) in equation 1.

P(5)=\frac{4}{36}

p(5) = \frac{1}{9}

Using formula.

p(Not\ E) + p(E) = 1

p(Not\ 5) + p(5) = 1

Now we substitute p(5) in above equation.

p(Not\ 5) + \frac{1}{9} = 1

p(Not\ 5) = 1-\frac{1}{9}

p(Not\ 5) = \frac{9-1}{9}

p(Not\ 5) = \frac{8}{9}

Therefore, the sum of two six-sided dice roll outcome is not equal to 5.

p(Not\ 5) = \frac{8}{9}

6 0
3 years ago
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