aianjie

 

The correct answer is D

Using the total probability rule, we can compute the P(B):

P(B) = [P(B|A) × P(A)] + [P(B|AC) × P(AC)]

P(B) = [0.5 × 0.4] + [0.2 × 0.6] = 0.32

Using Bayes’ formula, we can solve for P(A|B):

P(A|B) = [ P(B|A) / P(B) ] × P(A) = [0.5 / 0.32] × 0.4 = 0.625

aianjie

 

 

The correct answer is D

The relative frequency is found by dividing the frequency of the interval by the total number of frequencies:7/16=43.8%

aianjie

 

2、How is the relative frequency of an interval computed?

A) By dividing the sum of the two interval limits by 2.

B) By dividing the frequency of that interval by the sum of all frequencies.

C) By multiplying the frequency of the interval by 100.

D) By subtracting the lower limit of the interval by the upper limit.

aianjie

 

The correct answer is B

The relative frequency is the percentage of total observations falling within each interval. It is found by taking the frequency of the interval and dividing that number by the sum of all frequencies.

aianjie

 

The relative frequency of the second class is:

A) 10.0%.

B) 0.0%.

C) 16.0%.

D) 43.8%.

aianjie

 

The sample size is:

A) 1.

B) 16.

C) 5.

D) 50.

aianjie

 

The correct answer is B

The sample size is the sum of all of the frequencies in the distribution, or 3 + 7 + 3 + 2 + 1 = 16.

aianjie

 

17、The probabilities that three students will earn an A on an exam are 0.20, 0.25, and 0.30, respectively. If each student’s performance is independent of that of the other two students, the probability that all three students will earn an A is closest to:

A) 0.0150.

B) 0.0075.

C) 0.0010.

D) 0.7500.

aianjie

 

The correct answer is A

Since the events are independent, the probability is obtained by multiplying the individual probabilities. Probability of three As = (0.20) × (0.25) × (0.30) = 0.0150.

aianjie

 

AIM 3: Explain the relative frequency or the empirical definition of probability.

1、

Return, R	Frequency
–10% up to 0%	3
0% up to 10%	7
10% up to 20%	3
20% up to 30%	2
30% up to 40%	1

The number of intervals in this frequency table is:

A)    5.

B)    1.

C)   16.

D)   50.