4.5

set.seed(450)
x <- rnorm(10000, mean = 4, sd = 2)

# A
pnorm(2, 4, 2) - pnorm(-2, 4, 2) 

[1] 0.1573054

mean(abs(x) < 2)

[1] 0.1552

# B
pnorm(0, 4, 2)

[1] 0.02275013

mean(exp(x) < 1)

[1] 0.0216

# C
(1 - pnorm(sqrt(3), 4, 2)) + pnorm(-sqrt(3), 4, 2)

[1] 0.8736757

mean(x^2 > 3)

[1] 0.8725