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Department of Statistics and Computer Information Systems
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Baruch College, City University of New York
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Test 2: Course: STA 2000 Time: 90 minutes
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Instructor: Balwant Singh Gill
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Last Name____Torres_____ First Name _______Anahy___________
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ID__23862348__________
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Note: 1. Underline and/or highlight your answer for the following questions
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2. Weight: 20. Each of the 10 questions has same weightage
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3. Email your test by 5:30 PM after which you will be considered absent.
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4. Write your comments if you find no answer to encircle in the question
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5. Join session and ask question if any to clarify your confusion
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Q1. In a society, there are only female and male children and their birth rate is assumed
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equally likely. Current record reveals that 550 females have been delivered among 1000
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deliveries. The approach of probability and probability of next delivery among those
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families will be
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a. a priori probability, 0.50
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b. empirical probability, 0.55
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c. subjective probability, 0.55
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d. empirical probability, 0.50
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Q2. Presume that there are only male and female children in a community with chances of
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their birth equally likely. If there are four children in each of the families in the
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community, the probability that a randomly selected family will have all female
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children is
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a. 0.1250
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b. 0.8750
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c. 0.9375
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d. 0.0625
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Q3. 36% of New Yorkers are single and 20% are HIV infected, whereas 12% are single and
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HIV infected. If it is known that a selected individual is married, the probability that
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he/she is HIV infected is
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a. 0.875
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b. 0.125
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c. 0.750
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d. 0.250
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Q4. Approximately 80% of all part time college students in US are females. A random
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sample of 256 these students is selected. The sample proportion p of part time females
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has approximately normal distribution with mean proportion of all possible samples
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and standard deviation of all possible sample proportion will be
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a. 0.8, 0.025
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b. 0.2, 0.025
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c. 1.0, 0.25
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d. None of a, b, c
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Q5. The survival rate of COVID-19 patients is 97% in a country. Two patients among them
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are randomly selected. The probability that at least one of the patients will survive is
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a. 0.9999
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b. 0.9409
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c. 0.0009
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d. 0.9991
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Q6. The alphabet Z in the question denotes standard normal variable and P denotes
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probability. If P(Z ≤ Z1) =0.4000 and P(Z ≥ Z2)=0.4000 then
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a. Z1 < Z2
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b. Z1 < 0
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c. Z2 > 0
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d. Each one of a, b, c is correct
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Q7. Annual family medical expenses for all families in US has normal distribution.
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95% confidence interval estimates of annual family medical expenses from a random
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Sample of 400 families are ($1000, $1200). The Sample Mean annual family medical
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expenses used to calculate confidence interval estimate is:
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a. $1000
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b. $1200
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c. $1400
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d. $1100
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Q8. A statistical analysis of 10000 long-distance telephone calls made from a large office
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indicates that the length of these calls is normally distributed with m = 200 seconds and
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σ = 50 seconds. Among 10% shorter calls, the longest call will be of length close to
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a. 264 seconds
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b. 164 seconds
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c. 136 seconds
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d. 100 seconds
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Q9. Price per gallon of unleaded gasoline at service stations in New York City is normally
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distributed with μ = $3.2 and σ = 25 cents. If there are 3000 service stations in the city,
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the expected number of service stations that have a price per gallon for unleaded
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gasoline less than $3.00 or more than $3.4 are.
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a. 626
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b. 1271
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c. 568
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d. 3000
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Q10. An economic analyst is interested in to estimate the proportion of new immigrants in
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US in 2008. The analyst wants to be 95% confident to estimate the proportion and she
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can tolerate a maximum of ±2% error in the estimate from the real proportion, the
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largest number of individuals that at least be included in the random sample:
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a. 2401
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b. 2351
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c. 1849
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d. less than 30
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