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54. 2067 Q No. 7 In a group of students 30 study maths, 24

study physics, 22 study chemistry, 14 study maths only, 8
study physics only, 6 study maths and chemistry, 2 study
maths and physics only and 8 study none. How many
students are in the group? How many study chemistry only?
How many study all three subjects?

User Xariez
by
5.3k points

1 Answer

5 votes

Explanation:

the 8 that study none have no impact on the other sub-groups, we only need to add them at the end for the full number of students in the group.

30 study math, 14 study math only.

that leaves 30-14 = 16 that study math and something else.

2 study math and physics only, that leaves 16-2 = 14 to study math and chemistry or all 3.

24 study physics. 8 study physics only.

that leaves 24-8 = 16 that study physics and something else.

2 study math and physics only, that leaves 16-2 = 14 to study physics and chemistry or all 3.

so, we know from the perspective of math :

14 math only

2 math and physics only

6 math and chemistry

the total for math must be 30, but we have no Venn segment missing for math.

but we are still missing 8 students of math we cannot place anywhere.

therefore, there must be a mistake in the problem description.

I assume it should be "6 study math and chemistry only".

then we can place the remaining 8 students in the central part that study all 3.

then from the perspective of physics :

8 physics only.

2 math and physics only

8 study all 3.

since we need a total of 24, there are 6 remaining, and one open Venn segment : 6 study physics and chemistry only.

from the perspective of chemistry :

6 study math and chemistry only.

6 study physics and chemistry only.

8 study all 3.

in total we need 22 students.

that are 2 remaining and one item Venn segment : 2 study chemistry only.

the total number of students is therefore :

# study math only = 14

+

# study physics only = 8

+

# study chemistry only = 2

+

# study math and physics only = 2

+

# study math and chemistry only = 6

+

# study physics and chemistry only = 6

+

# study all 3 = 8

+

# study none = 8

=

54 students in the group.

2 study chemistry only.

8 study all 3 subjects.

User ACuria
by
5.9k points