GATE 2023 BM – Question 9

General Aptitude · Quantitative Aptitude: Data Interpretation, Arithmetic and Number Computation · 2 marks · Multiple choice

There are 1000 people, of whom 100 have a disease. In pooled testing, samples are divided into groups of five. Each group is tested once; if it is positive, each of its five members is tested individually. What is the maximum total number of tests?

700
600
800
1000

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Correct answer: (A) 700

Explanation

There are 1000/5=200 initial pool tests. The greatest number of positive pools occurs when the hundred positive people lie in different pools, giving one hundred positive pools. These require 100×5=500 individual follow-up tests. Maximum total is 200+500=700, A, under the stated ideal testing model.

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