Introduction to the Practice of Statistics 9th edition by David S. Moore Test bank

 A)0.62%
 B)2.28%
 C)47.72%
 D)49.38%
 
 
200.The temperature at any random location in a kiln used for manufacturing bricks is Normally distributed with a mean of 1000°F and a standard deviation of 50°F.  When glazed bricks are put in the oven, if the temperature is below 900°F, they will discolor. If the bricks are placed randomly throughout the kiln, what percentage of glazed bricks will discolor?
 A)0.62%
 B)2.28%
 C)47.72%
 D)49.38%
 
 
201.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)62
 B)57
 C)44
 D)40
 
 
202.The preparation time to mail envelopes with a weekly report to all executives in a company has a Normal distribution with a mean of 35 minutes and a standard deviation of 2 minutes. On 95% of such occasions, the mailing preparation takes less than x minutes. What is the value of x?
 A)31.71
 B)34.75
 C)35.25
 D)38.29
 
 
203.A softdrink machine can be regulated so that it discharges an average of m ounces per cup. If the ounces of fill are Normally distributed with a standard deviation of 0.4 ounces, what value should m be set at so that 6-ounce cups will overflow only 2% of the time?
 A)5.18
 B)5.60
 C)6.00
 D)6.82
 
 
204.The weights of packets of cookies produced by a certain manufacturer have a Normal distribution with a mean of 202 grams and a standard deviation of 3 grams. What is the weight that should be stamped on the packet so that only 1% of the packets are underweight?
 A)195 grams
 B)202 grams
 C)209 grams
 D)There is not enough information to tell.
 
 
205.A company produces packets of soap powder labeled “Giant size 32 ounces.” The actual weight of soap powder in such a box has a Normal distribution with a mean of 33 ounces and a standard deviation of 0.7 ounces. To avoid dissatisfied customers, a box of soap is considered underweight if it weighs less than 32 ounces. To avoid losing money, the top 5% (the heaviest 5%) is labeled overweight.  What proportion of boxes is underweight?
 A)0.0766
 B)0.2420
 C)0.7580
 D)0.9234
 
 
206.A company produces packets of soap powder labeled “Giant size 32 ounces.” The actual weight of soap powder in such a box has a Normal distribution with a mean of 33 ounces and a standard deviation of 0.7 ounces. To avoid dissatisfied customers, a box of soap is considered underweight if it weighs less than 32 ounces. To avoid losing money, the top 5% (the heaviest 5%) is labeled overweight.  How heavy does a box have to be in order for the box to be labeled overweight?
 A)31.60 ounces
 B)31.85 ounces
 C)34.15 ounces
 D)34.40 ounces
 
 
207.Chocolate bars produced by a certain machine are labeled with 8.0 ounces. The distribution of the actual weights of these chocolate bars is Normal with a mean of 8.1 ounces and a standard deviation of 0.1 ounces. A chocolate bar is considered underweight if it weighs less than 8.0 ounces.  What proportion of chocolate bars weighs less than 8.0 ounces?
 A)0.159
 B)0.341
 C)0.500
 D)0.841
 
 
208.Chocolate bars produced by a certain machine are labeled with 8.0 ounces. The distribution of the actual weights of these chocolate bars is Normal with a mean of 8.1 ounces and a standard deviation of 0.1 ounces. A chocolate bar is considered underweight if it weighs less than 8.0 ounces.  What proportion of chocolate bars weighs between 8.2 and 8.3 ounces?
 A)0.136
 B)0.477
 C)0.636
 D)0.819
 
 
209.Chocolate bars produced by a certain machine are labeled with 8.0 ounces. The distribution of the actual weights of these chocolate bars is Normal with a mean of 8.1 ounces and a standard deviation of 0.1 ounces. A chocolate bar is considered underweight if it weighs less than 8.0 ounces.  How should the chocolate bar wrappers be labeled so that only 1% of such bars are underweight?
 A)7.77 ounces
 B)7.87 ounces
 C)8.23 ounces
 D)8.33 ounces
 
 
210.A market research company employs a large number of typists to enter data into a computer database. The time it takes for potential new typists to learn the computer system is known to have a Normal distribution with a mean of 90 minutes and a standard deviation of 18 minutes. A candidate is automatically hired if she learns the computer system in less than 100 minutes. A cut-off time is set at the slowest 10% of the learning distribution. Anyone slower than this cut-off time is definitely not hired.  What proportion of candidates takes more than 2 hours to learn the computer system?