Question

Let z be a random variable with a standard normal distribution. Find the indicated probability. (Round your answer to four decimal places.) P(z ? ?0.25)

Let z be a random variable with a standard normal distribution. Find the indicated probability. (Round your answer to four decimal places.) P(z ? 1.24)

Let z be a random variable with a standard normal distribution. Find the indicated probability. (Enter your answer to four decimal places.) P(?2.20 ? z ? 1.08)

Answer 1

Let z be a random variable with a standard normal distribution. Find the indicated probability.

P(z ? ?0.25) = 0.4013

Look the following image :

Let z be a random variable with a standard normal distribution. Find the indicated probability. (Round your answer to four decimal places.) P(z ? 1.24)

P(z ? 1.24) = 1 - P(Z < 1.24 ).......(1)

P(Z < 1.24 ) = 0.8925

Put this value in equation (1), we get

P(z ? 1.24) = 1 - 0.8925 = 0.1075

Look the following image:

Let z be a random variable with a standard normal distribution. Find the indicated probability. (Enter your answer to four decimal places.) P(?2.20 ? z ? 1.08)

P(?2.20 ? z ? 1.08) = P(X < 1.08 ) - P( X < -2.20) -------( 2 )

P(X < 1.08 ) = 0.8599

P( X < -2.20) = 0.0139

Plug these values in equation 1, we get:

P(?2.20 ? z ? 1.08) = 0.8599 -  0.0139 = 0.8460