Answer:
a) The mean is 
b) The standard deviation is 
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
The probability a student selected at random takes at least 55.50 minutes to complete the examination equals 0.6915.
This means that when X = 55.5, Z has a pvalue of 1 - 0.6915 = 0.3085. This means that when 
So




The probability a student selected at random takes no more than 71.52 minutes to complete the examination equals 0.8997.
This means that when X = 71.52, Z has a pvalue of 0.8997. This means that when 
So




Since we also have that 





Question
The mean is 
The standard deviation is 
Answer:
Hello!
`~~~~~~~~~~~~`
(2a-b)^2 -4(2a-b) -13 =

~~~~~~~~~~~~`
Step-by-step explanation: All you have to do is Factor the polynomial.
Hope this helped you. Brainliest would be nice!
______________❤︎______________
<span>The point where two rays meet to form an angle is called the
Vertex
and vertex became an angle
the corner of polygon are also called vertex
so i conclude option A is correct from above
hope it helps</span>
Answer:
8 1/4
General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Algebra I</u>
<u>Algebra II</u>
- Distance Formula:

Step-by-step explanation:
<u>Step 1: Define</u>
<em>Identify</em>
Point (-1, -3.75)
Point (-1, 4.5)
<u>Step 2: Find distance </u><em><u>d</u></em>
Simply plug in the 2 coordinates into the distance formula to find distance <em>d</em>
- Substitute in points [Distance Formula]:

- [√Radical] (Parenthesis) Subtract:

- [√Radical] Evaluate exponents:

- [√Radical] Add:

- [√Radical] Evaluate:

Answer:
r = 2
Step-by-step explanation:
We have the formula of
Now, it is given that
........ (1)
And we have to find the value of r which satisfy the above equation.
So,
Now, we have to use the trial method to find the value of r.
For r = 1,
Hence, r can not be 1.
Now, put r = 2,
Therefore, r = 2 (Answer)