Question

1. Find each of the probabilities for a normal distribution (be sure to write your answer using the correct format for probability) (2 pts)
   1. p( z > 2.25)
   2. p( z > -1.20)
   3. p(-1.80 < z < 0.20)
   4. p( -0.90 < z < -0.60)

Answer 1

solution

P(z > 2.25) =1 - P(z < 2.25)

Using z table,
= 1 -0.9878

=0.0122

probability=0.0122

(b)

P(z > -1.20) =1 - P(z < -1.20)

Using z table,
= 1 -0.1151

=0.8849

probability=0.8849

(c)

P( -1.80< Z <0.20 )

= P(Z <0.20 ) - P(Z <-1.80 )

Using z table,  

= 0.5793 -0.0359

=0.5434

probability=0.5434  

  

(D)

P( -0.90< Z <-0.60 )

= P(Z <-0.60 ) - P(Z <-0.90 )

Using z table,  

= 0.2743 -0.1841

=0.0902

probability=0.0902