MathematicsMediumHigh School (11–12)Statistics and Probability › StatisticsAPA-LevelIBAEEE (Amrita)AMUEEEAP EAPCET
Created by StemPy LabA data set has mean and variance . Every value is multiplied by . What is the variance of the new data set?
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← Two brands of light bulbs are tested. Brand X has a mean life of 800 hours and a standard deviation of 56 hours. Brand Y has a mean life of 1200 hours and a standard deviation of 72 hours. Which brand has the more consistent life, and what is its coefficient of variation?A group of 10 students has a standard deviation of 4 marks and a group of 30 students has a standard deviation of 8 marks. A student says that the standard deviation of all 40 is (10 × 4 + 30 × 8)/40 = 7 marks. What is wrong with this? →
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