Question

A box that a box of 600 electric bulbs contain 12 defective bulbs. One bulb is taken out at a random from this box. What is the probabillity that it is a non-defective bulb?
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Answer 1

$$\begin{gathered} \mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{bulbs}=600 \\ \mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{possible}\mathrm{outcomes}=600 \\ \mathrm{Number}\mathrm{of}\mathrm{defective}\mathrm{bulbs}=12 \\ \mathrm{Number}\mathrm{of}\mathrm{non}-\mathrm{defective}\mathrm{bulbs}=600-12=588 \\ \mathrm{Number}\mathrm{of}\mathrm{favourable}\mathrm{outcomes}=588 \\ \mathrm{P}\left(\mathrm{getting}\mathrm{a}\mathrm{non}-\mathrm{defective}\mathrm{bulb}\right)=\frac{\mathrm{Number}\mathrm{of}\mathrm{favourable}\mathrm{outcomes}}{\mathrm{Total}\mathrm{number}\mathrm{of}\mathrm{possible}\mathrm{outcomes}}=\frac{588}{600}=\frac{147}{150} \end{gathered}$$