Answer:
Explanation:
Let's use a Venn diagram to help us visualize the information given in the problem. We can start with three overlapping circles representing Physics (P), Chemistry (C), and Biology (B), and then fill in the numbers given:
P
/ \
/ \
/ \
CP BP
\ /
\ /
\ /
B
We know that 6 students study pure Chemistry, so we can write this number in the circle for Chemistry (C). We also know that 10 students study pure Physics and 8 students study pure Biology, so we can write these numbers in the circles for Physics (P) and Biology (B), respectively:
P (10)
/ \
/ \
/ \
CP (18) BP (21)
\ /
\ /
\ /
B (8)
C (6)
Now we can use the information given in the problem to fill in the remaining numbers:
22 students study Physics and Biology, so this number goes in the overlap between P and B: PB = 22
21 students study Chemistry and Biology, so this number goes in the overlap between C and B: CB = 21
We don't know the number of students who study Physics and Chemistry only, but we can use the fact that 6 students study pure Chemistry to figure it out. Since 18 students study Chemistry and Physics in total, and 6 of them study pure Chemistry, the remaining 18 - 6 = 12 students must study both Chemistry and Physics but not Biology. We can write this number in the overlap between C and P: CP = 12.
P (10)
/ \
/ \
/ \
CP (12) BP (21)
\ /
\ /
\ /
B (8)
C (6)
Now we can find the total number of students by adding up all the numbers in the Venn diagram:
Total = P + C + B - (CP + CB + PB) + (CPB)
Total = 10 + 6 + 8 - (12 + 21 + 22) + 0
Total = 19
Therefore, the total number of students in the class is 19.