# normal distribution

• Mar 2nd 2011, 07:57 AM
mathsohard
normal distribution
Suppose that the scores on the town's manual dexteritiy test are normal with mean 12 and standarad deviation 3. If eight randomly selected individuals take the test, what is the probability that everyone of the eight scores at least 14 assuming they are acting independently???(Review the table for the normal distribution)

how can I do this?? :( have exam in one hour but can't figure it out
• Mar 2nd 2011, 12:40 PM
poirot
Quote:

Originally Posted by mathsohard
Suppose that the scores on the town's manual dexteritiy test are normal with mean 12 and standarad deviation 3. If eight randomly selected individuals take the test, what is the probability that everyone of the eight scores at least 14 assuming they are acting independently???(Review the table for the normal distribution)

how can I do this?? :( have exam in one hour but can't figure it out

they collectively have a mean of 96 and variance 72 so sd =sqrt(72). So you now have a new random variable with those parameters. so z=(112-96)/sqrt(72)