Question

In a batch of 960 calculators, 8 were found to be defective. What is the probability that a calculator chosen at random will be defective? Write the probability as a percent. Round to the nearest tenth of a percent if necessary

Answer 1

Answer: 0.8%

Step-by-step explanation:

Given : In a batch of 960 calculators, 8 were found to be defective.

i.e. Total calculators =960

Number of defective calculator = 8

We know that the probability of any event is given by :-

$\dfrac{\text{No. of favorable outcomes}}{\text{Total outcomes}}\\\\=\dfrac{8}{960}=0.00833333333333$

In percent, $0.00833333333333\times100=0.833333333333\%\\\\\approx0.8\%\ \ \ [\text{Rounding to the nearest tenth.}]$

Hence, the probability that a calculator chosen at random will be defective=0.8%

Answer 2

This is a case of empirical (observed) probability.  Historically speaking, 8 out of 960 calculators were found to be defective.  

Thus P(defective calculator) = 8/960, or 0.008333 ...

As a percent, this is 0.8%.