Mobile homes are tightly constructed for energy conservation. This can lead to a buildup of indoor pollutants. The paper "A Survey of Nitrogen Dioxide Levels Inside Mobile Homes"† discussed various...

Mobile homes are tightly constructed for energy conservation. This can lead to a buildup of indoor pollutants. The paper "A Survey of Nitrogen Dioxide Levels Inside Mobile Homes"† discussed various aspects of NO2 concentration in these structures.

(a)

For one sample of mobile homes in the Los Angeles area, the mean NO2 concentration in kitchens during the summer was 38.52 ppb, and the standard deviation was 11.16. Making no assumptions about the shape of the NO2 distribution, what can be said about the percentage of observations between 16.20 and 60.84? (Round the answer to the nearest whole number.)

at least %

(b)

Inside what interval is it guaranteed that at least 89% of the concentration observations will lie for the distribution in part (a)?

,

(c)

For a sample of mobile homes that were not in Los Angeles, the average kitchen NO2 concentration during the winter was 23.88 ppb, and the standard deviation was 16.00. Do these values suggest that the histogram of sample observations did not closely resemble a normal curve? (Hint: What is

x − 2s?)
Yes

No