Question

I need help understanding normal distribution

Answer 1

ok

Answer 2

example of the problems are A normal distribution has a mean of 45 and a standard deviation of 4. Find the
probability that a randomly selected x-value from the distribution is in the given interval.
6. Between 37 and 49
7. Between 41 and 53

Answer 3

and
A normal distribution has mean x and a standard deviation σ. Find the probability for a
randomly selected x-value from the distribution.
1. P(x ≥ x + 2σ)
2. P(x ≤ x + 2σ)

Answer 4

I dont know how to do this

Answer 5

all normal distributions can be standardized

Answer 6

the formula to map X onto Z is:\[z=\frac{x-mean}{sd}\]

Answer 7

i dont understand this

Answer 8

...and i cant read minds. can you be more informative about your confusion?

Answer 9

I dont understand any of this....
in general i dont understand this

Answer 10

the standard deviation is a measure of how far away from the mean a given value is.

the picture you posted shows the usual probabilites for a given measure of standard deviation.

Answer 11

there is about a 34% probability that a value is 1 standard deviation to the left, or to the right of the mean .... and the other percentages give you the same kind of information

Answer 12

so what we should prolly do, is determine how many standard deviations from the mean value the given values actually are

Answer 13

yea i know that 1-68 2-95 3-99.7

Answer 14

A normal distribution has a mean of 45 and a standard deviation of 4. Find the
probability that a randomly selected x-value from the distribution is in the given interval.

\[x-mean=sd(n)\]\[n=\frac{x-mean}{sd}\]

6. Between 37 and 49;
\[n_1=\frac{37-45}{4}\]
\[n_2=\frac{49-45}{4}\]

Answer 15

can you give me the values for n1 and n2?

Answer 16

n1- 103/4

Answer 17

these values will tell us how many "standard deviations" we are away from the mean, and then we can compare that to the picture you posted to add up the percentage

\[n_1=\frac{37-45}{4}=\frac{-8}{4}=-2\]