MATH-CLOSE-DOOR-1

Form past experience it is known 90% of one years old children can distinguish their mother’s voice from the voice of similar sounding female. A random sample of 20 one years old given the voice recognize test. Find the probability that all children recognize mother’s voice.

• 0.122

• 0.500

• 1.200

• 0.222

From past experience, it is known 90 percent of one year’s old children can distinguish their mother’s voice of a similar sounding female. A random sample of one year’s old are given this voice recognize test. Find the standard deviation that all 20 children recognize their mother’s voice.

• 0.12

• 1.34

• 0.88

• 1.43

From past experience it is known 90 percent of one year old children can distinguish their mothers voice of a similar sounding female. A random sample of one year’s old are given this voice recognize test. Find the probability that at least 3 children didn’t recognize their mother’s voice.

• 0.677

• 0.323

• 0.729

• 0.271

From past experience, it is known 90% of one year old children can distinguish their mother voice from the voice of a similar sounding female. A random sample of 20 one year olds are given this voice recognition test. Let the random variable x denote the number of children who do not recognize their Mother's voice. Find the mean of x.

• 20

• 2

• 4

• 1

In a hotel it is known that 20% of the total reservation will be cancelled in the last minute. What is the probability that out of 15 reservation that there will be more than 8 but less than 12 will cancelled?

• 0.0084

• 0.0784

• 0.000784

• 0.784

In a hotel it is known that 20% of the hotel reservation will be cancelled in the last minute. What is the probability that there will be less than 2 reservations cancelled out of 4 reservations?

• 0.6498

• 0.5629

• 0.3928

• 0.4096

In a hotel it is known than 20% of the total reservation will be cancelled in the last minute. What is the probability that these will be fewer than 2 reservation cancelled out of 4 resevations?

• 0.6498

• 0.5629

• 0.3928

• 0.8192

3 randomly chosen senior high school students were administered a drug test. Each student was evaluate as positive to the drug test (P) or negative to the drug test (N). Assume the possible combinations of the 3 students drug test evaluation as PPP,PPN,PNP,NPP,PNN,NPN,NNP,NNN. Assume the possible combination is equally likely and knowing that 1 student get a negative result, what is the probability that all 3 students get a negative result?

• 1/8

• 1/7

• 7/8

• 1/4

3 randomly chosen senior high school students was administered a drug test. Each student was evaluated as positive to the drug test(P) or negative to the drug test (N). Assume the possible combinations of the three student’s drug test evaluation as PPP,PPN,PNP,NPP,PNN,NPN,NNP,NNN. Assuming each possible combination is equally likely what is the probability that all 3 students get positive results?

• 1/8

• ¾

• ¼

• ½

Three randomly chosen senior high school students was administered a drug test. Each student was evaluated as positive to the drug test (P) or negative to the drug test (N). Assume the possible combinations of the three students' drug test evaluation as PPP, PPN, PNP, NPP, PNN, NPN, NNP, NNN. Assuming each possible combination is equally likely, what is the probability that all three students get negative results ?

• 4/8

• 2/7

• 7/8

• 3/7