Question

If one bulb is taken out at random from a box of 600 electric bulbs containing 12 defective bulbs, then the probability of getting a non-defective bulb is?
A) 0.78
B) 0.65
C) 0.98
D) 0.85

Answer 1

Hint : To calculate the probability of getting a non-defective bulb, we first need to find its number which will become our favorable outcome, then we can apply the formula of probability so as to obtain the required answer because the total number of outcomes are already given in the question as well.
0 ${\text{Probability = }}\dfrac{{{\text{Favorable outcomes}}}}{{{\text{Total outcomes}}}}$

Complete step-by-step answer :
According to the question, we have:
Total number of bulbs (Total outcomes) = 600
Number of defective bulbs = 12
Therefore, number of non-defective bulb (Favorable outcomes) is given as:
600 – 12 = 588
Substituting these values in the formula to calculate probability, we get:
${\text{Probability = }}\dfrac{{{\text{Favorable outcomes}}}}{{{\text{Total outcomes}}}}$
${\text{P(non defective bulbs) = }}\dfrac{{588}}{{600}}$
$= 0.98$
Thus, the probability of getting a non-defective bulb from a box of 600 electric bulbs containing 12 defective bulbs is 0.98, option C).
So, the correct answer is “Option C”.

Note : Probability denotes the chance of occurring.
Probability = 0 means it is an impossible event and will never occur whereas probability = 1 means it is a sure event and will definitely occur.
Probability of an event can never take a negative value.
Remember that some of all the possible outcomes of an event is always equal to 1 and this can also be used to verify the answer.
Hence another approach of this answer could be:
1 - P(getting a defective bulb).