Question

the same as Q1: Assume the printer cartridges in average can print 12,000 pages with 800 pages as its standard deviation (µ= 12000, σ = 800), and it is a bell-shaped distribution for the number of pages (X) it can print before running of of ink.(X is a random variable, isn't it?)

Using Emprical Rules to answer:

What is the chance that your cartridger can print less than 12,800 pages? That means in Math: Prob(X < 12,800) or in short: P(X < 12,800) = ?

(ex., if the answer is 6.5%, write only 0.065, ignore the % sign).

Answer 1

Solution :

Given that ,

mean = = 12000

standard deviation = = 800

P(x < 12800) = P[(x - ) / < (12800 - 12000) / 800]

= P(z < 1.00)

Using empirical rule

= ±   = 0.68

= 0.68 / 2 = 0.34

= -

= 0.50 - 0.34

= 0.16