1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
stich3 [128]
3 years ago
8

The compressive strength of concrete is being tested by a civil engineer who tests 12 specimens and finds that the sample mean i

s 3259.9 psi and the sample standard deviation is 35.57 psi. Compressive strength is known to be normally distributed.
Find a 95% confidence interval for mean compressive strength.
Mathematics
1 answer:
ki77a [65]3 years ago
6 0

Answer:

The 95% confidence interval for mean compressive strength is:

3237.3\leq \mu\leq 3282.5

Step-by-step explanation:

We have a sample of n=12 specimens, with sample mean=3259.9 and sample standard deviation = 35.57.

We know the population is normally distributed.

For a 95% confidence interval and df=n-1=11, the t-statistic is t=2.201.

Then, the CI can be expressed as:

M-t*s/\sqrt{N}\leq \mu\leq M+t*s/\sqrt{N}\\\\3259.9-2.201*35.57/\sqrt{12}\leq \mu\leq 3259.9+2.201*35.57/\sqrt{12}\\\\ 3259.9-22.6\leq \mu\leq 3259.9+22.6\\\\3237.3\leq \mu\leq 3282.5

You might be interested in
How much flour does Carlos use?
Nostrana [21]
HEY THERE.

THE CORRECT ANSWER IS....... CARLOS USES 0.75
4 0
3 years ago
How do the values in Pascal’s triangle connect to the coefficients?
damaskus [11]

Explanation:

Each row in Pascal's triangle is a listing of the values of nCk = n!/(k!(n-k)!) for some fixed n and k in the range 0 to n. nCk is <em>the number of combinations of n things taken k at a time</em>.

If you consider what happens when you multiply out the product (a +b)^n, you can see where the coefficients nCk come from. For example, consider the cube ...

  (a +b)^3 = (a +b)(a +b)(a +b)

The highest-degree "a" term will be a^3, the result of multiplying together the first terms of each of the binomials.

The term a^b will have a coefficient that reflects the sum of all the ways you can get a^b by multiplying different combinations of the terms. Here they are ...

  • (a +_)(a +_)(_ +b) = a·a·b = a^2b
  • (a +_)(_ +b)(a +_) = a·b·a = a^2b
  • (_ +b)(a +_)(a +_) = b·a·a = a^2b

Adding these three products together gives 3a^2b, the second term of the expansion.

For this cubic, the third term of the expansion is the sum of the ways you can get ab^2. It is essentially what is shown above, but with "a" and "b" swapped. Hence, there are 3 combinations, and the total is 3ab^2.

Of course, there is only one way to get b^3.

So the expansion of the cube (a+b)^3 is ...

  (a +b)^3 = a^3 + 3a^2b +3ab^2 +b^3 . . . . . with coefficients 1, 3, 3, 1 matching the 4th row of Pascal's triangle.

__

In short, the values in Pascal's triangle are the values of the number of combinations of n things taken k at a time. The coefficients of a binomial expansion are also the number of combinations of n things taken k at a time. Each term of the expansion of (a+b)^n is of the form (nCk)·a^(n-k)·b^k for k =0 to n.

6 0
3 years ago
Can someone help me with this problem 3(x+1)=11 I need it step by step
Nataly [62]

Answer:

x = 2.66666667

Step-by-step explanation:

3(x + 1) = 11

We multiply both x and 1 by 3 and get

3x + 3 = 11

Now we subtract 3 from both sides

3x + 3 - 3 = 11 - 3

3x = 8

Now divide both sides by 3

3x/3 = 8/3

x = 2.66666667

(っ◔◡◔)っ ♥ Hope It Helps ♥

6 0
2 years ago
Read 2 more answers
Ill i need to know is the fraction please
murzikaleks [220]

Answer:

6/10 i think

Step-by-step explanation:

625 divided by 15 is 41.6 so i'd be 40+1+6/10

6 0
3 years ago
Read 2 more answers
Hey! i need help plz
tia_tia [17]
X=6 and y=-9. Not sure if y is correct since I kind of rushed but I hope this helps!
6 0
3 years ago
Other questions:
  • If S (3,-4) is translated 5 units left and 3 units up, what is the ordered pair of S?<br>​
    13·1 answer
  • The nth term of a sequence is 2n-1.
    5·1 answer
  • AC = 12 CE = 15 AB = 4 What is BD
    12·1 answer
  • The town swimming pool is d feet deep. The width of the pool is 10 feet greater than 5 times the depth. The length of the pool i
    7·1 answer
  • N is an integer.<br><br> write the values of n such that -15&lt;3n≤6
    5·2 answers
  • A cookie recipe calls for 2 eggs and 3 cups of flour. Nisha plans to increase the recipe
    5·2 answers
  • The longest side of a triangle is 80cm more than the second and 130cm more than the shortest side and its perimeter is 540cm. fi
    13·1 answer
  • HELP ASAP ! PLEASE I LOVE YOU MAY GOD BLESS YOU &lt;3 :)
    5·2 answers
  • Obtuse triangle ABC is isosceles and m∠B is 142°.
    8·1 answer
  • If you have y+t+x-7+8 what is the naswer
    6·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!