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anonymous
 one year ago
The life expectancy of a typical lightbulb is normally distributed with a mean of 2,000 hours and a standard deviation of 27 hours. What is the probability that a lightbulb will last between 1,975 and 2,050 hours? all I know about this question is that I have to use a zscore
anonymous
 one year ago
The life expectancy of a typical lightbulb is normally distributed with a mean of 2,000 hours and a standard deviation of 27 hours. What is the probability that a lightbulb will last between 1,975 and 2,050 hours? all I know about this question is that I have to use a zscore

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Here, we want to know the probability that bulb falls between and 1975 and 2050. The "trick" to solving this problem is to realize the following: P( 1975 < X < 2050 ) = P( X < 2050 )  P( X < 1975 ) dw:1435247712590:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so to find P(X<2050) find z value=20502000(which is the mean)/27 =50/27 look up this z value in the z table and u get the probability of a bulb having life expectancy less than 2050 similarly calculate it for bulb having life expectancy less than 1975 subtract both of them and u get the answer

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I dont have a ztable :(

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay so z value for 2050 comes out to be 1.85 so if u look in the table , the value corresponding to 1.85 is 0.9678 so the prob =0.9678

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0now calculate P(X<1975)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0How would I calculate that? P((0.9678)<1975) ? @nitishdua31

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh no, 0.96 is the probability of a bulb having life expectancy less than 2050 now you have to calculate the probability of a bulb having life expectancy less than 1975

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0coz when you subtract them , you get the probability of the bulb having life expectancy between them

anonymous
 one year ago
Best ResponseYou've already chosen the best response.00.17619 0.32381 0.79165 0.96784 that bottom answer looks like the one you gave earlier

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0these are the choices @nitishdua31

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@dan815 can you help explain ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I'm so lost right now @nitishdua31

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0take a look at this the first figure shows what you have to calculate, and we can find that by subtracting second and third figure now, we already calculated second, i.e. 0.96 now we have to calculate third

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the third being the bottom?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0which represents less than 1975

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@ganeshie8 can u help ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.00.5 for the Z? @nitishdua31
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