<h2><u>
Answer with explanation:</u></h2>
The confidence interval for population mean (when population standard deviation is unknown) is given by :-
![\overline{x}-t^*\dfrac{s}{\sqrt{n}}< \mu](https://tex.z-dn.net/?f=%5Coverline%7Bx%7D-t%5E%2A%5Cdfrac%7Bs%7D%7B%5Csqrt%7Bn%7D%7D%3C%20%5Cmu%3C%5Coverline%7Bx%7D%2Bz%5E%2A%5Cdfrac%7Bs%7D%7B%5Csqrt%7Bn%7D%7D)
, where n= sample size
= Sample mean
s= sample size
t* = Critical value.
Given : n= 25
Degree of freedom : ![df=n-1=24](https://tex.z-dn.net/?f=df%3Dn-1%3D24)
![s=\ $19.95](https://tex.z-dn.net/?f=s%3D%5C%20%2419.95)
Significance level for 98% confidence interval : ![\alpha=1-0.98=0.02](https://tex.z-dn.net/?f=%5Calpha%3D1-0.98%3D0.02)
Using t-distribution table ,
Two-tailed critical value for 98% confidence interval :
![t^*=t_{\alpha/2,\ df}=t_{0.01,\ 24}=2.4922](https://tex.z-dn.net/?f=t%5E%2A%3Dt_%7B%5Calpha%2F2%2C%5C%20df%7D%3Dt_%7B0.01%2C%5C%2024%7D%3D2.4922)
⇒ The critical value that should be used in constructing the confidence interval = 2.4922
Then, the 95% confidence interval would be :-
![93.36-(2.4922)\dfrac{19.95}{\sqrt{25}}< \mu](https://tex.z-dn.net/?f=93.36-%282.4922%29%5Cdfrac%7B19.95%7D%7B%5Csqrt%7B25%7D%7D%3C%20%5Cmu%3C93.36%2B%282.4922%29%5Cdfrac%7B19.95%7D%7B%5Csqrt%7B25%7D%7D)
![=93.36-9.943878< \mu](https://tex.z-dn.net/?f=%3D93.36-9.943878%3C%20%5Cmu%3C93.36%2B9.943878)
![=93.36-9.943878< \mu](https://tex.z-dn.net/?f=%3D93.36-9.943878%3C%20%5Cmu%3C93.36%2B9.943878)
![=83.416122< \mu](https://tex.z-dn.net/?f=%3D83.416122%3C%20%5Cmu%3C103.303878%5Capprox83.4161%3C%5Cmu%3C103.3039)
Hence, the 98% confidence interval for the mean repair cost for the dryers. = ![83.4161](https://tex.z-dn.net/?f=83.4161%3C%5Cmu%3C103.3039)
Question is Incomplete, Complete question is given below.
Prove that a triangle with the sides (a − 1) cm, 2√a cm and (a + 1) cm is a right angled triangle.
Answer:
∆ABC is right angled triangle with right angle at B.
Step-by-step explanation:
Given : Triangle having sides (a - 1) cm, 2√a and (a + 1) cm.
We need to prove that triangle is the right angled triangle.
Let the triangle be denoted by Δ ABC with side as;
AB = (a - 1) cm
BC = (2√ a) cm
CA = (a + 1) cm
Hence,
Now We know that
![(a- b)^2 = a^2+b^2 - 2ab](https://tex.z-dn.net/?f=%28a-%20b%29%5E2%20%3D%20a%5E2%2Bb%5E2%20-%202ab)
So;
![{AB}^2= a^2 + 1^2 -2\times a \times1](https://tex.z-dn.net/?f=%7BAB%7D%5E2%3D%20a%5E2%20%2B%201%5E2%20-2%5Ctimes%20a%20%5Ctimes1)
![{AB}^2 = a^2 + 1 -2a](https://tex.z-dn.net/?f=%7BAB%7D%5E2%20%3D%20a%5E2%20%2B%201%20-2a)
Now;
![{BC}^2 = (2\sqrt{a})^2= 4a](https://tex.z-dn.net/?f=%7BBC%7D%5E2%20%3D%20%282%5Csqrt%7Ba%7D%29%5E2%3D%204a)
Also;
![{CA}^2 = (a + 1)^2](https://tex.z-dn.net/?f=%7BCA%7D%5E2%20%3D%20%28a%20%2B%201%29%5E2)
Now We know that
![(a+ b)^2 = a^2+b^2 + 2ab](https://tex.z-dn.net/?f=%28a%2B%20b%29%5E2%20%3D%20a%5E2%2Bb%5E2%20%2B%202ab)
![{CA}^2= a^2 + 1^2 +2\times a \times1](https://tex.z-dn.net/?f=%7BCA%7D%5E2%3D%20a%5E2%20%2B%201%5E2%20%2B2%5Ctimes%20a%20%5Ctimes1)
![{CA}^2 = a^2 + 1 +2a](https://tex.z-dn.net/?f=%7BCA%7D%5E2%20%3D%20a%5E2%20%2B%201%20%2B2a)
![{CA}^2 = AB^2 + BC^2](https://tex.z-dn.net/?f=%7BCA%7D%5E2%20%3D%20AB%5E2%20%2B%20BC%5E2)
[By Pythagoras theorem]
![a^2 + 1 +2a = a^2 + 1 - 2a + 4a\\\\a^2 + 1 +2a= a^2 + 1 +2a](https://tex.z-dn.net/?f=a%5E2%20%2B%201%20%2B2a%20%3D%20a%5E2%20%2B%201%20-%202a%20%2B%204a%5C%5C%5C%5Ca%5E2%20%2B%201%20%2B2a%3D%20a%5E2%20%2B%201%20%2B2a)
Hence, ![{CA}^2 = AB^2 + BC^2](https://tex.z-dn.net/?f=%7BCA%7D%5E2%20%3D%20AB%5E2%20%2B%20BC%5E2)
Now In right angled triangle the sum of square of two sides of triangle is equal to square of the third side.
This proves that ∆ABC is right angled triangle with right angle at B.
<span>39 & 16.5 = -22.5
30 & 12.4 = -17.6
28 & 10.4 = -17.6
19 & 10.3 = -8.7
23 & 11.2 = -11.8
if the values are y values you will subtract them from each other to get the numerical value and because they all go from a larger number to a smaller number the rate is a negative. if they were from a smaller value to a larger value teh rates of change would be positive.
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I believe cats, cause they do things on their own but also dogs too. This is a very hard question.