Question

A random sample of 420 new Ford trucks showed that 105 required repairs within the first warranty year.What is the estimate for the probability that a new Ford truck will need repairs within the first warranty year?
using the info above, what is the estimate for the probability that a new Ford truck will not need repairs within the first warranty year?

Answer 1

The probability of an event P(n), is equal to the number of the outcomes of that event n(E), divided by the total number of outcomes, or the sample space, n(S)

so $P(n)= \frac{n(E)}{n(S)}$


$P(truck need rapair within the first year)=$

$\frac{n(truck need rapair within the first year)}{n(trucks)} = \frac{105} {420}= 0.25$

The probability of an event = 1 - probability of the same event not to happen

so P(not need repair within the first year)=1-0.25=0.75


Answer: a) 0,25; b) 0,75