# Questions on Probability

**Topics:**Standard deviation, Random variable, Normal distribution

**Pages:**1 (260 words)

**Published:**December 3, 2012

2.A manufacturer who produces medicine bottles finds that 0.1% of the bottles are defective. The bottles are packed in the boxes of 500 bottles. A drug manufacturer buys 100 boxes from the producer of bottles . Using suitable probability distribution , find how many boxes will contain (i) No defectives, (ii) At least two defectives ? Answer (i) 0.6065 X 100= app 61 bottles, , (ii) 10 bottles app. 3. Mean and standard deviation of chest measurement of 1200 soldiers are 85 and 5 cm respectively. How many of them are expected to have their chest measurement exceeding 95 cm assuming a normal distribution.( Prob.=0.9772, Answer =1173) 4. In a certain Poisson frequency distribution the frequency corresponding to 2 successes is half the frequency corresponding to 3 successes. Find its mean and standard deviation.( Mean=6, Sd= Sq. root of 6) 5. A soft-drink vending machine is set so that the amount of drink dispensed is a random variable with a mean of 200 ml. And a standard deviation of 15 ml. Find the probability that the average amount dispensed in a random bottle is at least 204 ml.? ( Ans=0.3949)

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