Answer:
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the complement rule and the normal standard table and we got:
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution problem
Let X the random variable that represent the variable of interest of a population, and for this case we know the distribution for X is given by:
Where 
and 
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the complement rule and the normal standard table and we got:
First, let us break down 28 hours 36 minutes into minutes.
Number of minutes taken to grade 220 essays = (28 x 60) + 36 = 1680 + 36 = 1716 minutes
Now, we can find the average time taken to grade an essay by dividing the time taken to grade 220 essays by 220.
Average amount of time taken to grade an essay = 
= 7.8 minutes, or 7 minutes and 48 seconds
Answer:
look up the paper because i had that same paper
Step-by-step explanation:
Seems to be an arythmetic sequence
Sn=[n(a1+an)]/2
where
Sn means sum of all terms up the nth term
n=number of terms
a1=first term
an=nth term
so from 86 to the 22th term is from a1 to a22
find teh sequence
miknus 7 each time
an=a1+d(n-1)
an=87-7(n-1)
find 22n term
a22=87-7(22-1)
a22=87-7(21)
a22=87-147
a22=-60
S22=[22(87-60)]/2
S22=[22(27)]/2
S22=594/2
S22=297
the sum is 297
9514 1404 393
Answer:
(a, b, c) = (-0.425595, 11.7321, 2.16667)
f(x) = -0.425595x² +11.7321x +2.16667
f(1) ≈ 13.5
Step-by-step explanation:
A suitable tool makes short work of this. Most spreadsheets and graphing calculators will do quadratic regression. All you have to do is enter the data and make use of the appropriate built-in functions.
Desmos will do least-squares fitting of almost any function you want to use as a model. It tells you ...
a = -0.425595
b = 11.7321
c = 2.16667
so
f(x) = -0.425595x² +11.7321x +2.16667
and f(1) ≈ 13.5
_____
<em>Additional comment</em>
Note that a quadratic function doesn't model the data very well if you're trying to extrapolate to times outside the original domain.
