Probability and sampling distribution Name Institutional affiliations Chapter Five Quiz 1 Solution. Mean=2500 Standard deviation=500 By using the 68-95-99.7 rule, nearly 68% of the light bulbs have a life time between: Mean- standard deviation=2500-500 =2000 Mean+ standard deviation=2500+500 =3000 An approximate number of 95% have a life of between Mean-2 standard deviations =2500-(2*500) = 1500 and Mean+2 standard deviations=2500+ (2*500) =3500 95.7% of the bulbs have a life of between Mean-3 standard deviations=2500-(3*500) =1000 and Mean +3 standard deviations=2500+3 standard deviations =2500+ (3*500) =4000 This means that 49.85% (95.7%/2) of the bulbs have a life that is inferior to 2500 (mean) Z-score = value – (Mean / SD) =2500-2500 500 =0 From the z table 50% is the corresponding percentile of bulbs with life of less than 2500 hours. Quiz 2 Solution Mean = 370 Standard deviation=5, Standard deviation = 1 68-95-99.7 rule states that: 68% of all the observations lie within 1 SD of the mean. =370-5 =365 hours AND =370+5 =375 hours. Z (for 365 value) = (365-370)/5 =-1 which corresponds to 15.87% percentile of the Z score table Z (for the 375 value) = (375-370)/5 =1 which corresponds to 84.13% percentile of the Z score table Therefore: 84.13%-15.87% = 68.26% of all scores fall between 1 standard deviation of the mean on either side. Question 3 Solution: Mean=$60 Standard deviation= $12 60-12 = 48 and 60+12 = 72 $48 and $72 Quiz 4 Solution Mean = $50, Standard deviation = $10 Data value = $50/$10 25th percentile z-score =-0.674 -0.674= (y - 50) / 10 6.74 =

Zika virus: Transmission form Introduction The Zika virus belongs to the Flaviviradae family, was found for the first time in a monkey called Rhesus febrile and in...

Zika virus: cases and prevention Introduction The World Health Organization (WHO) has confirmed that Zika is a virus caused through the mosquito bite which is...

Zeus The King of Greek mythology Introduction Zeus is the Olympic God of heaven and thunder, the king of all other gods and men and, consequently, the main figure...

Zeus's punishment to Prometheus Introduction Prometheus, punished by Zeus Prometheus, punished by Zeus. Prometheus is a ‘cousin’ of Zeus. He is the son of the...

## Leave feedback