QBA STANDARD EXAM SHEET 2025/2026 QUESTIONS AND
SOLUTION RATED A+
✔✔The accompanying table contains the overall download and upload speeds in mbps
for 13 carriers. Complete parts (a) and (b) below.
a) Construct a scatter plot with download speed on the X-axis and upload speed on the
Y-axis. Choose the correct scatter plot below.
b) Researchers believe that carriers with a higher overall download speed also have a
higher overall upload speed. Does the scatter plot confirm or contradict this belief? -
✔✔b) The scatter plot
contradicts confirms
the belief because there is a strong, increasing
relationship.
✔✔The following is a set of data from a sample of n=5.
7 2 10 6 8
a. Compute the mean, median, and mode.
b. Compute the range, variance, standard deviation, and coefficient of variation.
c. Compute the Z scores. Are there any outliers?
d. Describe the shape of the data set. - ✔✔use excel
✔✔The following is a set of data from a sample of n=6.
9 6 11 9 5 20
a. Compute the first quartile (Q1), the third quartile (Q3), and the interquartile range.
b. List the five-number summary.
c. Construct a boxplot and describe the shape. - ✔✔use excel
✔✔The following is a set of data for a population with N=10.
5
12
4
12
2
5
5
10
6
7
a. Compute the population mean.
b. Compute the population standard deviation. - ✔✔a. The population mean is μ= 6.8.
b. The population standard deviation is σ= 3.25.
✔✔Four coins are tossed.
a. Give an example of a simple event.
, b. Give an example of a joint event.
c. What is the complement of getting a head on the first coin?
d. What does the sample space consist of? - ✔✔Simple event: Getting a head on the
first coin
Joint event: Getting
a tail on the third coin and a tail on the first coin.
Complement: Getting
a tail on the first coin.
Sample space:
Getting a head or a tail
on any of the four coins.
✔✔Suppose that E and F are two events and that P(E and F)=0.1 and P(E)=0.8.
What is P(F|E)? - ✔✔0.125 [P(E and F)/P(E)]
✔✔If P(A)=0.7, P(B)=0.6, and P(A and B)=0.56, are A and B independent? - ✔✔No
✔✔If P(A)=0.8, P(B)=0.7, and A and B are independent, find P(A and B). - ✔✔P(A and
B) = 0.56 (0.8*0.7)
✔✔The increase or decrease in the price of a stock between the beginning and the end
of a trading day is assumed to be an equally likely random event. What is the probability
that a stock will show an increase in its closing price on six consecutive days? - ✔✔The
probability that a stock will show
an increase
in its closing price on
six consecutive days is
0.0156. (use poisson excel)
✔✔Assume a Poisson distribution.
a. If λ=2.5, find P(X=6).
b. If λ=8.0, find P(X=1).
c. If λ=0.5, find P(X=2).
d. If λ=3.7, find P(X=9). - ✔✔Use Poisson Excel guide
✔✔Given the probability distributions shown to the right, complete the following parts.
a. Compute the expected value for each distribution.
b. Compute the standard deviation for each distribution.
c. What is the probability that x will be at least 3 in Distribution A and Distribution B?
d. Compare the results of distributions A and B. - ✔✔(use discrete variable excel guide)
✔✔Given an exponential distribution with λ=23, what is the probability that the arrival
time is:
a. less than X=0.2?
b. greater than X=0.2?
SOLUTION RATED A+
✔✔The accompanying table contains the overall download and upload speeds in mbps
for 13 carriers. Complete parts (a) and (b) below.
a) Construct a scatter plot with download speed on the X-axis and upload speed on the
Y-axis. Choose the correct scatter plot below.
b) Researchers believe that carriers with a higher overall download speed also have a
higher overall upload speed. Does the scatter plot confirm or contradict this belief? -
✔✔b) The scatter plot
contradicts confirms
the belief because there is a strong, increasing
relationship.
✔✔The following is a set of data from a sample of n=5.
7 2 10 6 8
a. Compute the mean, median, and mode.
b. Compute the range, variance, standard deviation, and coefficient of variation.
c. Compute the Z scores. Are there any outliers?
d. Describe the shape of the data set. - ✔✔use excel
✔✔The following is a set of data from a sample of n=6.
9 6 11 9 5 20
a. Compute the first quartile (Q1), the third quartile (Q3), and the interquartile range.
b. List the five-number summary.
c. Construct a boxplot and describe the shape. - ✔✔use excel
✔✔The following is a set of data for a population with N=10.
5
12
4
12
2
5
5
10
6
7
a. Compute the population mean.
b. Compute the population standard deviation. - ✔✔a. The population mean is μ= 6.8.
b. The population standard deviation is σ= 3.25.
✔✔Four coins are tossed.
a. Give an example of a simple event.
, b. Give an example of a joint event.
c. What is the complement of getting a head on the first coin?
d. What does the sample space consist of? - ✔✔Simple event: Getting a head on the
first coin
Joint event: Getting
a tail on the third coin and a tail on the first coin.
Complement: Getting
a tail on the first coin.
Sample space:
Getting a head or a tail
on any of the four coins.
✔✔Suppose that E and F are two events and that P(E and F)=0.1 and P(E)=0.8.
What is P(F|E)? - ✔✔0.125 [P(E and F)/P(E)]
✔✔If P(A)=0.7, P(B)=0.6, and P(A and B)=0.56, are A and B independent? - ✔✔No
✔✔If P(A)=0.8, P(B)=0.7, and A and B are independent, find P(A and B). - ✔✔P(A and
B) = 0.56 (0.8*0.7)
✔✔The increase or decrease in the price of a stock between the beginning and the end
of a trading day is assumed to be an equally likely random event. What is the probability
that a stock will show an increase in its closing price on six consecutive days? - ✔✔The
probability that a stock will show
an increase
in its closing price on
six consecutive days is
0.0156. (use poisson excel)
✔✔Assume a Poisson distribution.
a. If λ=2.5, find P(X=6).
b. If λ=8.0, find P(X=1).
c. If λ=0.5, find P(X=2).
d. If λ=3.7, find P(X=9). - ✔✔Use Poisson Excel guide
✔✔Given the probability distributions shown to the right, complete the following parts.
a. Compute the expected value for each distribution.
b. Compute the standard deviation for each distribution.
c. What is the probability that x will be at least 3 in Distribution A and Distribution B?
d. Compare the results of distributions A and B. - ✔✔(use discrete variable excel guide)
✔✔Given an exponential distribution with λ=23, what is the probability that the arrival
time is:
a. less than X=0.2?
b. greater than X=0.2?
