VKC ScienceChemistry for written exams Telegram

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 · 2024 · Mains Paper III

Q5(a). Confidence interval of a mean at the 99 % level

Question

A set of seven measured values resulted in X̄ = 14.74 (±0.38). Calculate the confidence interval including the true value at a confidence level (CL) of 99.0%. [Given: t₉₉.₀ (degrees of freedom): 4.604 (4), 4.032 (5), 3.707 (6), 3.499 (7)]

Answer in brief

ν = N − 1 = 6, so t = 3.707; μ = 14.74 ± 0.53: the true value lies between 14.21 and 15.27 at the 99.0 % confidence level.

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

The handwritten model answer pages open with the VKC plan.
Read the whole 2024 solution2024 question paper

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 →

Coversconfidence intervalStudent's tconfidence limitsdegrees of freedomstandard deviation

All parts of Question 5