1. As part of a promotion for a new type of cracker, free trial samples are offered to shoppers in a local supermarket. The probability that a shopper will buy a packet of crackers after tasting the free sample is 0.200. Different shoppers can be regarded as independent trials. If is the proportion of the next 100 shoppers that buy a packet of the crackers after tasting a free sample, then has approximately a
A. N (0.2, 0.0016) distribution.
B. N (0.2, 0.04) distribution.
C. N (0.2, 4) distribution.
2. As part of a promotion for a new type of cracker, free samples are offered to shoppers in a local supermarket. The probability that a shopper will buy a packet of crackers after tasting the free sample is 0.200. Different shoppers can be regarded as independent trials. If is the proportion of the next 100 shoppers that buy a packet of the crackers after tasting a free sample, then the probability that fewer than 30% buy a packet after tasting a free sample is approximately (don't use the continuity correction)
A. 0.3000
B. 0.9938
C. Neither choice is correct.
3. Suppose that you are a student worker in the Statistics Department and agree to be paid by the Random Pay system. Each week the Chair flips a coin. If the coin comes up heads, your pay for the week is $80; if it comes up tails, your pay for the week is $40. You work for the department for 100 weeks (at which point you have learned enough probability to know the system is not to your advantage). The probability that , your average earnings in the first two weeks, is greater than $65 is
A. 0.2500.
B. 0.3333.
C. 0.5000.