It is possible to calculate mathematically the area under the normal curve between any two values of z.
However, tables/software have been developed to give the areas under the normal curve to the left of particular values of z. The function is the probability of Z<z, or P(Z<z).
The area between two values z1 and z2 (where z2>z1) is therefore
P(Z<z2)-P(Z<z1).
For example, to find the area between z1=1.5, z2=2.5
is
P(Z<2.5)-P(Z<1.5)
=0.99379-0.93319
=0.06060
(above values obtained by software, such as R)
For example, the value P(Z<2.5) can be calculated using
P(Z<2.5)=erf(2.5/sqrt(2))/2+1/2
where erf(x) is a mathematical function that does not have an explicit formula (calculated by summation of series, or tabulated).
Answer:
the percent of increase is 24%
Step-by-step explanation:
The percent of increase in general could be calculate as:

where Vf is final value and Vi is initial value.
From the question we know that Vi is equal to 25 and Vf is equal to 31. Replacing this values on the equation we get:

That's mean that at second attempt the percent of increase is 24%, taking into account that at the first attempt a student get 25 questions correct.
let x =the number
Step-by-step explanation:
81+x=3x-39
group like terms
81+39=3x-x
120=2x
120/2=2x/2
60=x
therefore x =60
Answer: hope it helps
Step-by-step explanation:
2x+11 absolute value equals 2x+11, then 2x+11=7, subtract 11 from itself, and 7 you get 2x=4 divide both sides by 2 an you get -2=x.
Answer:
there is a total of 20 students in the class because 60% of 20 is 12
Step-by-step explanation:
pls answer my recent question :(