Quiz 2.2

A company produces ceramic floor tiles that are supposed to have surface area of 16.0 square inches. Due to variability in the manufacturing process, the actual surface area has a normal distribution with a mean of 16.1 square inches and a standard deviation of 0.2 square inches. The proportion of tiles produced by the process with surface area less than 16.0 square inches is A 0.6915 B 0.4115 C 0.3173 D 0.3085 E 0.1915

0.3085

Birthweights at a local hospital have Normal distribution with a mean of 110 oz. and a standard deviation of 15 oz. Which of the following is the proportion of infants with birth weights under 95 oz. ? A 0.500 B 0.815 C 0.340 D 0.160 E 0.025

0.160

Using the standard normal distribution tables, the area under the standard normal curve corresponding to -0.5 > Z > 1.2 is A 0.3661 B 0.5764 C 0.8849 D 0.2815 E 0.3085

0.5764

Using the standard Normal distribution tables, the area under the standard Normal curve corresponding Z < 1.1 is: A 0.8643 B 0.8438 C 0.1357 D 0.2704 E 0.8413

0.8643

Using standard Normal distribution tables, the area under the standard Normal curve corresponding to Z > -1.22 is A 0.4129 B 0.1151 C 0.1112 D 0.8888 E 0.8849

0.8888

A company produces packet of soap powder that are labeled "Giant Size 32 Ounces." The actual weight of soap powder in a box has a normal distribution with a mean of 33 oz. and a standard deviation of 0.7 oz. 95% of packets actually contain more than x oz. of soap powder. what is x? A 31.60 B 34.40 C 34.15 D 31.85 E 32.88

31.85

If the heights of 99.7% of American men are between 5'0" and 7'0", what is your estimate of the standard deviation of the height of American men? (Assume the heights of American Men are Normally Distributed). A 1" B 2" C 4" D 6" E 12"

4"

The scores on a university examination are normally distributed with a mean of 62 and a standard deviation of 11. If the bottom 5% of students will fail the course, what is the lowest mark that a student can have and still be awarded a passing grade? A 43 B 62 C 44 D 40 E 57

44

IQs among undergraduates at Mountain Tech are approximately Normally distributed. The mean undergraduate IQ is 110. About 95% of undergraduates have IQs between 100 and 120. The standard deviation of these IQs is about A 20 B 15 C 25 D 5 E 10

5

A soft-drink machine can be regulated so that it discharges an average of ? oz. per cup. If the ounces of fill are Normally distributed with a standard deviation of 0.4 oz., what value should ? be set at so that 98% of 6-oz. cups will not overflow? A 6.00 B 6.82 C 5.18 D 6.60 E 6.18

5.18

You are chatting with the principal of a local high school. The topic of SAT scores comes up, and the principal mentions that SAT scores at the school are Normally distributed. She doesn't remember the mean or the standard deviation, but she does remember that the upper and lower quartiles are 500 and 600. The standard deviation of SAT verbal scores is closest to A 550 B 75 C 100 D 25 E 50

75

The time to complete a standardized exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given? A 92.8 min B 79.8 min C 84 min D 61.6 min E 78.4 min

78.4 minutes

A company produces packets of soap powder labeled "Giant Size 32 Ounces." The actual weight of soap powder in a box has a normal distribution with a mean of 33 oz and a standard deviation of 0.8 oz. What proportion of packets are underweight? A 0.159 B 0.115 C 0.841 D 0.106 E 0.212

0.106

Birthweights at a local hospital have a Normal distribution with a mean of 110 oz. and a standard deviation of 15 oz. The proportion of infants with birthweights between 125 oz. and 140 oz. is about A 0.270 B 0.135 C 0.815 D 0.680 E 0.475

0.135

The Normal curve below describes the death rates from heart disease per 100,00 people in developed countries in the 1990's (graph) A Mean = 190 Standard Deviation = 65 B M = 200 StD = 130 C M = 100 StD = 100 D M = 190 StD = 100 E M = 100 StD = 65

Mean = 190 Standard Deviation = 65