The chance of rain on any day in a region is 20%. You visit for three days. What is the probability of at least one rainy day? Clarification: assume rain on different days is independent, as the source solution does; the daily chance alone does not determine the answer.
Two dice each have 12 sides numbered 1 to 12. Roll both. What is the probability that the product of the top numbers is 12? Assume fair dice and independent rolls.
A unit square is repeatedly divided into four equal squares using side midpoints, as shown. What is the total area of the shaded squares? Count the four shaded squares actually shown; the last two have equal size.
Jason can paint a warehouse alone in 18 hours; Carla can do it alone in 12 hours. How many hours do they need working together at their usual constant rates?