# Table 1 Tasks used in this study

Task 1—“Maternity hospital” (misconception type: insensitivity to sample size):
In one hospital on a typical day, 45 babies are born. In another hospital, on a typical day, 15 babies are born. Every year the number of born girls and boys is approximately equal. In both hospitals, the number of days was counted when 60% of the newborns were boys. Which hospital had a greater number of such days?
a) The larger hospital (about 45 babies born per day)
b) The smaller hospital (about 15 babies per day)
c) The number of such days would be approximately equal in both hospitals.
Task 2—“Lotto” (misconception type: misconception of chance):
In the game where 7 numbers are drawn out of 39, choose the combination that is most likely to win.
a) 1, 2, 3, 4, 5, 6, 7
b) 12, 14, 16, 18, 20, 22, 24
c) 2, 7, 11, 38, 24, 15, 12
d) All have equal chance
Task 3—“Mobile phones” (misconception type: illusory correlation):
Two groups participate in a survey about the use of mobile phones. 70% of participants in the first group said that they used mobile phones while driving while 40% of participants in the second group stated the same. In the first group, there were 20 women and 10 men while in the second group there were 14 women and 16 men.
a) Men use mobile phone while driving more often than women.
b) Women use mobile phone while driving more often than men.
c) Based on the collected data, it is not possible to make conclusions about mobile phone usage with respect to gender.
Task 4—“IT engineer” (misconception type: equiprobability bias):
In one company 70% of employees hold a degree in information technology while 30% of employees hold law degree. One employee was randomly selected. His name is Mark, he is young, successful, and very driven. He likes to swim and exercises regularly.
What is the likelihood that Mark is an engineer in information technology?
a) 70%
b) 30%
c) 50%
Task 5—“R/W balls” (misconception type: biases in the evaluation of conjunctive and disjunctive events):
Choose the game which gives you the most chance to win.
a) Game 1: Draw a red ball from the bowl with half white and half red balls.
b) Game 2: Draw seven red balls from the bowl with 90% red balls and 10% white balls where after each draw the color is recorded and the ball is returned to the bowl.
c) Game 3: Draw at least one red ball out of seven drawings from the bowl with 90% white balls and 10% red balls. After each draw, the color is recorded and the ball is returned to the bowl.
Task 6—“Lawyer” (misconception type: base rate neglected):
Mark has been interested in theater and music since childhood. He loves art, and he is an opera fan. Which of the following claims is more likely?
a) Mark is a member of the Belgrade’s Philharmonics and plays clarinet.
b) Mark is a lawyer.
1. Correct answers are marked bold