Basic Applied Statistics 200
Normal Practice Exercises

Assume all the data sets in these exercises follow a normal curve closely enough that a normal approximation may be used. Use sketches as much as possible.

1. The mean is 100 points, standard deviation is 10 points.
   1. Find the proportion of values below 70 points.
   2. The middle 95% of the values are between what two point values?
2. The mean is 6 inches, standard deviation is 1.5 inches.
   1. Find the proportion of values below 6 inches.
   2. The shortest 16% are shorter than how many inches?
3. The mean is 20 cigarettes, standard deviation is 5 cigarettes.
   1. Find the proportion of values above 22.5 cigarettes.
   2. The top 10% are greater than how many cigarettes?
4. The mean is 165 lbs., standard deviation is 12 lbs.
   1. Find the proportion of values between 140 and 170 lbs.
   2. The lightest 2% are lighter than how many pounds?
5. The mean is 4 people, standard deviation is 1.3 people. Find the proportion of values less than 2 people.
6. The mean is 11 years, standard deviation is 2 years.
   1. Find the proportion of values less than 17 years.
   2. The longest 7% are longer than how many years?
7. The mean is $30,000; standard deviation is $8,000. Find the proportion of values between $20,000 and $22,000.
8. The mean is 120 mm., standard deviation is 20 mm. Find the proportion of values greater than 112 mm.
9. The mean is 6 feet, standard deviation is .2 feet. Find the proportion of values greater than 6.5 feet.
10. The mean is 60 degrees, standard deviation is 16 degrees. Find the proportion of values between 64 and 79 degrees.
11. The mean is 300 ml., standard deviation is 3 ml. Find the proportion of values
    1. less than 280 ml
    2. greater than 280 ml
    3. less than 315 ml
    4. greater than 315 ml.

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