Suppose that iq scores within a population are normally distributed with mean 100 and standard deviation 10. if we pick a person at random from this population, what it the probability that he or she has an iq score
(a) above 130?
(b) below 110?
(c) between 90 and 120?

a) Probability is 0.001

b) Below 110 is 0.84

c) Between 90 and 120 is 0.818

Step-by-step explanation:

We can calculate this using the cumulative normal distribution , by first standarizing our random variable X defined as IQ Scores  to a Z standard normal variable ( mean 1 - std 0 ) for the specific value we need :

a)

Z=X-mean/std = 130-100/10 =3.00

Then we can calculate:

P(X>130) = P(Z>3) = 1- P(Z<3) due to rules of probability.

This probability can be calculated with the function Norm.Distr(130,100,10,True) in  Excel or using the Z table looking for the value of Z = 3 in the rows and the value of the hundredths in Z in this case 0.00. If we do it in  excel we get:

1-P(Z<3)=1-0.9986=0.0013

b) We execute the same procedure as above now for 110

Z=110-100/10=1

P(X<110)=P(Z<1)=0.84

c) In this case the interval can be calculated as the area between the large an the low values.

Z1=120-100/10 = 2

Z2 =90-100/10= -1

P(90<X<120) = P(X<120)-P(X<90)=P(Z1<2)-P(Z2<-1)=0.977-0.158=0.818

she will most likely have 33  

step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.