Work Step by Step
The number of surveyed students who plan to take only Biology and Chemistry during their first year can be found by looking for the region/s that represents the intersection of Biology and Chemistry. The diagram shows that the region common to both chemistry and biology contains the cardinalities $8$ and $2$. Note, however, that the cardinality $2$ represents the region common to all three subjects. Since the one we are looking for is the number of students who will take only Chemistry and Biology (and not any other subject), then we should not include $2$ in our count. Therefore, only 8 students plan to take only Chemistry and Biology during their first year.