Math  Standard Deviation
 👍 0
 👎 0
 👁 74
Respond to this Question
Similar Questions

maths
the life span of an electric bulb is normally distribution with mean 5500 light hours and standard deviation of 1200 light hours . what is the probability that a randomly selected bulb which lasts more than 6000 light hours?
asked by ragul on December 31, 2015 
Statistics
The life of an electric light bulb is known to be normally distributed with a mean of 2000 hours and a std. of 120 hours. Find the probability that the life of such a bulb would be. (a) greater than 2150 hours (b) within the range
asked by Heidi on July 8, 2014 
math
1) A light bulb producing company states that its lights will last an average of 1200 hours with a standard deviation of 200 hours. A sample of 100 light bulbs from the company were tested and the researcher found that the average
asked by Alexus on July 16, 2012 
statistics
A new extendedlife light bulb has an average service life of 750 hours, with a standard deviation of 50 hours. If the service life of these light bulbs approximates a normal distribution, about what percent of the distribution
asked by MARIA on January 9, 2012 
Statistics
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life. Assuming that the life of the light bulb is normally distributed and that the standard deviation is known to be 40 hours, how many bulbs
asked by Blerp on November 16, 2012 
statistics
the life of light bulbs is distributed normally. The variance of the life time is 225 and the mean lifetime of a bulb is 590 hours. Find the probability of a bulb lasting for at most 603 hours. Yeah, WTF??? Why me!??!
asked by Logan on May 3, 2012 
Statistics
An industrial engineer has found that the standard household light bulbs produced by a certain manufacturer have a useful life that is normally distributed with a mean of 250 hours and a variance of 2500. (a) What is the
asked by bappy on March 11, 2014 
statistics
Suppose that the certain lifetimes of a certain light bulb are normally distributed with μ=1500 hours and σ=200. Find the probability that a light bulb will burn out in less than 1200 hours.
asked by Yenny on May 14, 2012 
statitics
a light bulb manufacture gaurentees that the mean life of a certain type of bulb is at least 875 hours. A random sample of 40 light bulbs has a mean life of 863 hours with a standard deviation of 50. a=0.04
asked by jamie on April 18, 2011 
Stats
A new extendedlife light bulb has an average service life of 750 hours, with a standard deviation of 50 hours. If the service life of these light bulbs approximates a normal distribution, about what percent of the distribution
asked by Stephanie F on December 13, 2011