Question

The amounts of nicotine in a certain brand of cigarette are normally distributed with a mean of 0.884 g and a standard deviation of 0.315 g. The company that produces these cigarettes claims that it has now reduced the amount of nicotine. In what range would you expect to find the middle 50% of amounts of nicotine in these cigarettes (assuming the mean has not changed)? Between and (Enter your answers in ascending order...smaller on left, larger on right. Also, enter your answers accurate to four decimal places.) If you were to draw samples of size 58 from this population, in what range would you expect to find the middle 50% of most average amounts of nicotine in the cigarettes in the sample? Between and (Enter your answers in ascending order...smaller on left, larger on right. Also, enter your answers accurate to four decimal places.)

Answer 1

1) for middle 50% values, critical z =0.6745

therefore corresponding interval =0.884 -/+ 0.6745*0.315 =between 0.6715 and 1.0965

2)for n=58:

sample size       =n=	58
std error=σx̅=σ/√n=	0.0414

therefore corresponding interval =0.884 -/+ 0.6745*0.0414 =between 0.8561 and 0.9119