Question

I will be grateful to be answered using excell

You have to include the Excel formulas used.

In an evaluation of progress, made to 400 managers, the average of the scores was 70 and its standard deviation was 8.0, what is the probability that, if we select a manager at random (among the 400 that were evaluated ), did he get 70 or more?

Z                              =             __________________________

1-Z                          +             __________________________

Probability          =             __________________________ = ____________________%

Answer 1

average of the scores of managers = 70

number of managers , n = 400

standard deviation of the scores of managers = 8

standard deviation of average of the scores of managers = standard deviation of the scores of managers / sqrt(n)

standard deviation of average of the scores of managers = 8/sqrt(400)

standard deviation of average of the scores of managers = 8/20

standard deviation of average of the scores of managers = 0.4

X be the average score of managers

P[ a manager at random get 70 or more score ] = P[ X > 70 ]

Z = ( X - mean )/ standard deviation

Z = ( 70 - mean )/ standard deviation

Z = ( 70 - 70 )/0.4

Z = 0

1 - Z = 1 - 0 = 1

To calculate probability

=NORM.DIST(70,70,0.4,TRUE) in excel 10

=NORMDIST(70,70,0.4,TRUE) in excel 7

How this works = NORM.DIST(x,mean,std,cumulative)

x = value at which you want to calculate probability

mean = average of data

std = standard deviation of data

cumulative = T if you want the probability till that point ( p value )

F if you want the probability at that exact point

Probability          = 0.5 = 50%