Use the standard normal distribution to find P(-2.25 < z < 1.25).?

2 Answers

• P(-2.25 < z < 1.25)

  = P(z = 2.25) + P(z = 1.25)

  = 0.48778 + 0.39435

  = 0.88213

• The following table (see link) gives the area from 0 to a certain point.

  P(-2.25 < z < 1.25) = P( 0 < x < 1.25) + P( 0 < x < 2.25)

  0.3944+0.4878=0.8822

  Note: P( -2.25 < x < 0) = P( 0 < x < 2.25) because of symmetry.