The water department checks the city water supply on a regular basis for contaminants such as xylenes. the water department take
s 200 samples and estimates that the concentration of xylenes in your drinking water is 3.5 ppb (parts per billion), with a standard deviation of 0.2 ppb.
assuming the samples were random and unbiased, how much confidence can you have in this data?
assuming the samples were random and unbiased, how much confidence can you have in this data?
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We have been given that during one period extreme cold, the average daily temperature decreased degree F each day. We are asked to find number of days it will take for the temperature to decrease by 9 degree F.
First of all we will convert our mixed fraction into improper fraction.
Now we will divide total temperature change (9) by average daily temperature change () to find number of days.
Dividing a number by a fraction is same as multiplying the number by reciprocal of the fraction.
Therefore, it will take 6 days for the temperature to decrease by 9 degree F.