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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper III

Q2(c). Q-test on five results for Fe in an iron ore

Question

The Fe content in an iron ore sample is analyzed at five different laboratories using the same analytical method. The Fe contents are given below as wt %: 60.5 %, 61.5 %, 68.5 %, 52.0 % and 62.5 %. Using the Q-test, find if any of the above data is due to accidental error and can be rejected. Given: Q95 for five analysis is 0.710.

Answer in brief

No result can be rejected. Q = 0.515 for 52.0 % and 0.364 for 68.5 %; both are below Q95 = 0.710.

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Topic notes: errors in chemical analysis, standard deviation, confidence limits and the Q-, t- and F-tests, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversQ-testDixon Q testoutlier rejectiongross erroriron ore analysis

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