Problem 2 · Drivers at the checkpoint
A percentage of a percentage: 75% of 40%.
Integer answer, at most 4 digitsDuring a checkpoint on a motorway, 60% of the cars that passed carried two or more people. In 25% of the cars carrying just one person, the driver was a man. What percentage of all the cars that passed the checkpoint were cars with a single person who was a female driver?
Copa Cangur · SCM
Medium
Closed answer
Reasoned solution
Key idea: the second percentage applies only to the group of single-occupant cars.
Cars with a single person: $100\% - 60\% = 40\%$ of the total. Of these, $25\%$ had a male driver, so $75\%$ had a female one:
$$0.75 \cdot 40\% = 30\%.$$
Answer: 30