# Compute -z_0.025, which is the quantile of the standard normal distribution 
# such that 0.025 of the area under the curve is to the left and 0.975 is to the right.
# That is, P(Z < qnorm(0.025)) = 0.025
qnorm(0.025)

# Compute -z_0.05, which is the quantile of the standard normal distribution 
# such that 0.1/2 = 0.05 of the data is to the left and 0.95 is to the right.
# That is, P(Z < qnorm(0.05)) = 0.05
qnorm(0.1/2)

# Compute -z_0.005, which is the quantile of the standard normal distribution 
# such that 0.01/2 = 0.005 of the data is to the left and 0.995 is to the right.
# That is, P(Z < qnorm(0.005)) = 0.005
qnorm(0.01/2)

# Compute z_0.025, which is the quantile of the standard normal distribution 
# such that 0.975 of the data is to the left and 0.025 is to the right.
# That is, P(Z < qnorm(0.975)) = 0.975
# qnorm(0.975) = -qnorm(0.025)
qnorm(0.975)