Page 152 - NUMINO Challenge_D2

2 Draw a Venn diagram as shown below. 4 If the number of students who participate in

Class 1 Piano both math and science competitions is smaller,
A Class 2 the number of students who participate in math
B competition is greater. If the number of
students who participate in both competitions is
It is not because a student who plays the the smallest, the number of students who do not
piano is not a class 1 student that he/she is a participate at all is 0. Therefore, there are
class 2 student. The student can be from 24 26 40 10 students who participated in
another class, than class 1 or class 2. both competitions. Therefore, the maximum
There can be students from class 1 among number of students who participate only in the
the students who play the piano and who are math competition is 24 10 14.
not class 2 students.
A and B need to be compared, but since
there is no standard, you do not know which
one is greater. Therefore, you cannot say
that there are more students who play the
piano in class 2.
Among the students who play the piano,
there can be students from other classes
besides class 1 and class 2.
Therefore, is correct.

3 Among the numbers from 1 to 20, the divisors

of 20 are 1, 2, 4, 5, 10, and 20, and the divisors
of 30 are 1, 2, 3, 5, 6, 10, and 15. Therefore,
when you write the numbers from 1 to 20 in a
Venn diagram as shown below, B has the fewest
numbers.

Numbers from 1 to 20

19

7 Divisors of 20 Divisor of 30 18

8 4 2 6D
5 10
20 B 3
1C
15
17

A 9 11 12 13 14 16

Answer Key