Statistics Been Stuck On This Need Help Please

Question

Suppose that the age that babies first walk can be modelled by a normal distribution with mean of 12 months and standard deviation of 1 month. Using the methods described in this​ lesson, simulate 1000 values from a normal distribution with mean of 12 and standard deviation of 1. Make sure you select​ "Use Fix​ Seed" of 12641 for consistency. This will create a column of values. Create a histogram of these values checking ​"Value above​ bar" to make it easier to answer the following questions. We can think of these 1000 simulations as recording the ages of first walk for 1000 randomly selected babies.

What percent of simulations were between 10 and 12​ months? Make sure to answer in a percent.

Answer 1

Prob( 10 < x < 12) = Prob ( (10-12)/1 < z < (12-12)/1 ) = Prob ( -2 < z < 0)

= Prob( z<0) - Prob(z<-2) = 0.5 - = 0.47725 = 47.725%