Question

A new phone from Company M will last on average 2.7 years before dying and needing major repair or replacement if well taken care of with a standard deviation of 0.8 years. What is the probability that a phone will need replacement before 1.5 years (if taken care of!)

Answer 1

0.067

Explanation:

Given that :

Average years for which phone will last (m) = 2.7 years

Standard deviation (σ) = 0.8 years

Probability that phone will need replacement before 1.5 years

X = 1.5

Find the Zscore :

Zscore = (x - m) / σ

Zscore = (1.5 - 2.7) / 0.8

Zscore = - 1 2 / 0.8

Zscore = - 1.5

Hence ;

P(Z < - 1.5) = 0.066807 (from z probability calculator)

= 0.067