- It is a continuous distribution described by a bell-shaped symmetric curve.
3.1. Normal Distribution in R-Programming
- Normal Distribution formula
- P(x= a) = dnorm
- P(x<=a) = pnorm
- P(x>a) = 1 - P(x<= a - 1) = 1 - pnorm(a-1)
- An electrical firm manufactures light bulbs that have a length of life that is normally distributed with mean equal to 800 hours and a standard deviation of 40 hours. Find the probability that a bulb burns between 778 and 834 hours.
- pnorm(834, 800, 40) - pnorm(778, 800, 40) = 0.5111778
- A certain type of storage battery lasts on the average 3.0 years, with a standard deviation of 0.5 year. Assuming that the battery lives are normally distributed, find the probability that a given battery will last less than 2.3 years.
- P(x <= 2.3) = pnorm(2.3, 3.0, 0.5) = 0.08075666