Porisma

A hint to get started

Translate intervals and tails into normal probabilities

Given X∼N(50,8)X\sim N(50,8), find

(i) P(48<X<54)P(48<X<54),

(ii) P(X>55)P(X>55),

(iii) P(X<52)P(X<52) and

(iv) P(∣X−51∣<3)P(|X-51|<3).

CJC · Lecture · Example 1

Identify the mean and take the square root of the variance.

Convert the event to an interval and sketch the shaded area.

Use normalcdf with lower bound, upper bound, mean and standard deviation in that order.

Read the worked solution