Stat Challenge (Lessons on Random Variables)

Which of the following is a discrete random variable?

• The height of the study table used for online class.

• The time to finish answering a Statistics and Protest.

• The number of COVID-19 recoveries.

• The average weight before and during the pandemic.

Which of the following is a continuous random variable?

• The number of grade 11 students attending synchronous classes.

• The average amount of electricity consumed monthly..

• The number of COVID-19 cases.

• The number of defective gadgets produced by a manufacturer.

   

Which of the following is NOT a true statement?

• Random variables can only have one variable.

• The value of a random variable could be zero.

• The probability of the value of a random variable could be 1/2.

• The sum of all probabilities in a probability distribution is always equal to one.

If two coins are tossed, which is not a possible value of the random variable for the number of heads?

• 0

• 1

• 2

• 3

Which of the following is NOT TRUE about expected value?

• Expected value is an important indicator of the fairness of the game and the performance of business.

• Expected value is an ideal way to make decisions because it allows you to quantify and incorporate risk into your decision making, as well as balance potentially good and bad outcomes in the same equation.

• A negative expected value indicates a higher chance of winning and it indicates that the game is fair, while in business, it indicates a higher chance of profit.

• A zero expected value indicates that the game is fair and in business, it represents the break-even point of the business.

Suppose three coins are tossed. Let H represent head and T represent tail. What is the sample space for this experiment?

• S = {TTT, TTH, THT, HTT, HHT, HTH, THH, HHH}

• S = {TTT, TTH, HHT, HHH}

• S = {TT, TH, HT}

• S = {T, H}

Matt is working at XYZ bookstore. While doing an inventory, he decided to see just how many books are being sold in a week. The number of books sold per day at the store varies as shown in the given probability distribution below. What is the probability that Matt will sell 5 books?

• 0.1 or 10%

• 0.2 or 20%

• 0.3 or 30%

• 0.5 or 50%

What is the probability that Matt will sell at LEAST 4 books?

• 0.20 or 20%

• 0.30 or 30%

• 0.70 or 70%

• 0.80 or 80%

What is the mean and variance of the probability distribution in the given situation in no. 7?

• Mean = 5.3, Variance = 3.81

• Mean = 5.8, Variance = 1.74

• Mean = 4.6, Variance = 26.6

• Mean = 5.3, Variance = 31.9

A religious organization plans to invest ₱10,000 to host a charity for the front liners. They expect to sell tickets worth ₱15,000. But if it rains on the day of the raffle, they won't sell any tickets and the organization will lose all the money invested. If the weather forecast for that day is 20% possibility of rain, is this a good investment?

• It is a good investment since there is a higher chance that it will not rain, thus, they can sell more tickets.

• It is not a good investment since there is still a chance of raining.

• It is either a good or bad investment.

• It cannot be determined.