Quiz Week 4

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least "C." Using the 68-95-99.7 rule, what percentage of students score below 62? a) 2.5% b) 16% c) 32% d) 5%

a

The R command pnorm(-2) + (1 - pnorm(2)) will return an approximate value of: a) 0.05 b) 0.50 c) 0.005 d) 0.25 e) 0.95

a

In a random sample of 50 children, 5 develop freckles after prolonged periods of sun exposure. The odds that a randomly chosen child WILL develop freckles are: a) 9 b) 0.1 c) 1.0 d) 0.2 e) None of the above

b

Scores on a university exam are Normally distributed with a mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least "C." Using R, the area under the standard Normal curve corresponding to Z > -1.62 is: a) 0.9956 b) 0.9474 c) 0.0044 d) 0.0526

b

Scores on the SAT verbal test in recent years follow approximately the N(515, 109) distribution. How high must a student score in order to place in the top 5% of all students taking the SAT? a) 301 b) 694 c) 336 d) 729

b

The appropriate command to return the cumulative probability associated with a value of 4 from a normal distribution with a mean of 6 and a standard deviation of 2 is: a) pnorm(2, 4, 6) b) pnorm(4, 6, 2) c) pnorm(2, 6, 4) d) pnorm(6, 4, 2)

b

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 oz and a standard deviation of 0.7 oz. To avoid having dissatisfied customers, the company says a box of soap is considered underweight if it weighs less than 32 oz. To avoid losing money, it labels the top 5% (the heaviest 5%) overweight. What proportion of boxes is underweight (i.e., weigh less than 32 oz)? a) 0.7580 b) 0.9236 c) 0.0764 d) 0.2420

c

If two events (A and B) are independent, then the probability that they both occur is: a) known as the MULTIPLICATION RULE, where Pr [A or B] = Pr [A] x Pr [B] - Pr [A and B] b) known as the ADDITION RULE, where Pr [A or B] = Pr [A] + Pr [B] c) known as the MULTIPLICATION RULE, where Pr [A and B] = Pr [A] x Pr [B] d) known as the ADDITION RULE, where Pr [A or B] = Pr [not A] + Pr [not B] - Pr [A and B] e) known as the ADDITION RULE, where Pr [A or B] = Pr [A] + Pr [B] - Pr [A and B]

c

Scores on a university exam are Normally distributed with a mean of 78 and a standard deviation of 8. The professor teaching the class declares that a score of 70 or higher is required for a grade of at least "C." Using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least "C"? a) 5% b) 32% c) 2.5% d) 16%

d

Scores on the SAT verbal test in recent years follow approximately the N(515, 109) distribution. The proportion of students scoring at least 600 is closest to a) 0.082 b) 0.782 c) 0.184 d) 0.218

d

Scores on the SAT verbal test in recent years follow approximately the N(515, 109) distribution. The proportion of students scoring between 460 and 550 is closest to: a) 0.626 b) 0.309 c) 0.681 d) 0.319

d

For any probability distribution, the R command to return Quantiles (outcome values) associated with a specified cumulative probability is a) p b) f c) r d) d e) q

e

The distribution describing the outcome of probabilities for all outcomes from tossing a coin 5 times is the: a) Binomial distribution b) Chi-square distribution c) Normal distribution d) Poisson distribution e) None of the above

e

The distribution that describes the probabilities of discrete counts based on sample mean and variance is a) the normal distribution b) the t-distribution c) the binomial distribution d) the Chi-square distribution e) the Poisson distribution

e

The probability distribution for the lengths of legs on 1000 randomly sampled fruit flies (measured in millimeters to 3 decimal places) would be: a) a discrete probability distribution b) a uniform distribution c) cannot be predicted in advance d) either a discrete or continuous distribution, depending on the actual results obtained e) a continuous probability distribution

e