Hi
What is the standard error of the distribution of the sample mean?
= 1.1
What proportion of the samples will have a mean useful life of more than 36 hours?
normalcdf(36,100, 34,1.1) |100 a placeholder 0r P(z >2/1.1) = 3.45%
What proportion of the sample will have a mean useful life greater than 33.5 hours?
normalcdf(33.5,100, 34,1.1) 0r P(z > -.5/1.1) = 67.53%
What proportion of the sample will have a mean useful life between 33.5 and 36 hours?
normalcdf(33.5,36, 34,1.1) 0r 67.53 - 3.45 = 64.08%
first are TI instructions(recommended) 'Or' is using z and z-calculator
Tables are fine. Calculators quicker..so as one not loses there train of thought as to important concepts.