Question

1 A set of scores measuring aggression is nor- mally distributed with a mean equal to 23 and a standard deviation equal to 2.5. Find the proportion: la) To the left of x 19.0 b) To the right of x 25.5 (c) Between the mean and x 19.0 d] To the left of x 25.5 lel To the right of x 19.0

Answer 1

a)

for normal distribution z score =(X-μ)/σ
here mean=       μ=	23
std deviation   =σ=	2.5000

probability =

P(X<19)

=

P(Z<-1.6)=

0.0548

b)

probability =

P(X>25.5)

=

P(Z>1)=

1-P(Z<1)=

1-0.8413=

0.1587

c)

probability =

P(19<X<23)

=

P(-1.6<Z<0)=

0.5-0.0548=

0.4452

d)

probability =

P(X<25.5)

=

P(Z<1)=

0.8413

e)

probability =

P(X>19)

=

P(Z>-1.6)=

1-P(Z<-1.6)=

1-0.0548=

0.9452