The think the answer for number 7 is A/10
Number 8 is C/16
<h2>
Answer with explanation:</h2>
The confidence interval for population mean is given by :-
(1)
, where
= sample mean
z* = critical value.
SE = standard error
and
,
= population standard deviation.
n= sample size.
As per given , we have


n= 15
It is known that ring diameter is normally distributed.
By z-table ,
The critical value for 95% confidence = z*= 1.96
A 99% two-sided confidence interval on the true mean piston diameter :
(using (1))

[Rounded to three decimal places]
∴ A 99% two-sided confidence interval on the true mean piston diameter = (74.020, 74.022)
By z-table ,
The critical value for 95% confidence = z*= 1.96
A 95% lower confidence bound on the true mean piston diameter:
(using (1))
[Rounded to three decimal places]
∴ A 95% lower confidence bound on the true mean piston diameter= 74.020
I have no idea good question though 69=y
(
+ 4)(
- 4)
To solve this question you must FOIL (First, Outside, Inside, Last) like so
First:
(x^2 + 4)(x^2 - 4)
x^2 * x^2
x^4
Outside:
(x^2 + 4)(x^2 - 4)
x^2 * -4
-4x^2
Inside:
(x^2 + 4)(x^2 - 4)
4 * x^2
4x^2
Last:
(x^2 + 4)(x^2 - 4)
4 * -4
-16
Now combine all the products of the FOIL together like so...
x^4 - 4x^2 +4x^2 - 16
Combine like terms:
x^4 - 4x^2 +4x^2 - 16
- 4x^2 +4x^2 = 0
x^4 - 16 <<<This is your answer
Hope this helped!
~Just a girl in love with Shawn Mendes