Statement: Of the 40 students in Class 11-B at Riverside School, 25 chose Physics and 22 chose Economics as an elective. Every student chose at least one of the two.
Conclusions:
I. Some students of Class 11-B chose neither Physics nor Economics.
II. At least 7 students of Class 11-B chose both Physics and Economics.
Which conclusions follow?

Only I followsCorrect answerYour answerOnly II followsCorrect answerYour answerNeither I nor II followsCorrect answerYour answerBoth I and II followCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

I does not follow: the statement says every student chose at least one of the two subjects, so I contradicts it.
II follows: $25 + 22 = 47$ choices were made by only 40 students, so $47 - 40 = 7$ students must have been counted twice, that is, chose both.
So only II follows.

Worth noting

When a statement gives numbers, a conclusion may be one short calculation away. Doing that calculation is not outside knowledge.

Concept: A numerical conclusion forced by the statement
Typical timeTypical: 105 s
Your timeYours: —

The rule this testsStatements and conclusions

Practise this chapter →

Ten questions from Statements, Conclusions and Assumptions, at your own pace.

Explanation