TestUstad

The average of 18 observations was calculated and it was 124. Later on it was discovered that two observations 46 and 82 were incorrect. The correct values are 64 and 28. The correct average of 18 observations is___________?

Correct answer: D. 122

  • A. 123
  • B. 137
  • C. 121
  • D. 122

Explanation

The originally recorded total is 18 x 124 = 2232. Replacing 46 and 82 by 64 and 28 changes the total by (64 + 28) - (46 + 82) = -36, so the corrected total is 2196 and the corrected average is 2196 ÷ 18 = 122. The likely mistake is option a, which may come from correcting only one of the two observations.

Written and checked by , MS Computer ScienceLast updated
Report an error

The more specific you are, the faster it gets fixed. A source beats an opinion.

Prefer email? [email protected]

About Averages

An average represents the total of a set of values divided by the number of values, and a weighted average gives different importance to different groups. Problems involve missing values, combined averages, replacement of observations, and changes in the average, so the total and count must be tracked separately.

Practise Arithmetic

1,060 free Arithmetic MCQs from Mathematics, each with the correct answer and an explanation. Unlimited attempts, no account needed.

Start a free Arithmetic testAll Arithmetic MCQs

Discussion

Stuck on an option, or know a faster way to get there? Ask or explain it here.

No comments yet. Be the first to explain this one.

Exams that ask Mathematics questions like this

Mathematics is on 76 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.

Lecturer Mathematics Test Mathematics80 MCQsNET Mathematics80 MCQsSubject Specialist Mathematics Test Mathematics80 MCQsATS Mathematics30 MCQsCA QAT Mathematics30 MCQsCTS Mathematics30 MCQsECAT Mathematics30 MCQsETEA Engineering Admission Test Mathematics30 MCQsETEA Recruitment Tests Mathematics30 MCQsGAT General Mathematics30 MCQsGIKI Mathematics30 MCQsNAT Mathematics30 MCQsNED Mathematics30 MCQsNTS Mathematics30 MCQsOTS Mathematics30 MCQsPIEAS Mathematics30 MCQsPTS Mathematics30 MCQsSTS Mathematics30 MCQsUTS Mathematics30 MCQsBCAT Mathematics25 MCQsISSB Mathematics25 MCQsCSS MPT Mathematics20 MCQsPAF Mathematics20 MCQsPAF Airman Mathematics20 MCQsPakistan Army Commissioned Officer Test Mathematics20 MCQsPakistan Navy Test Mathematics20 MCQsPatwari Test Mathematics20 MCQsPMA Long Course Test Mathematics20 MCQsPMD Mathematics20 MCQsComputer Operator Test Mathematics15 MCQsDEO Mathematics15 MCQsEducators ESE Test Mathematics15 MCQsEducators SESE Test Mathematics15 MCQsEducators SST Test Mathematics15 MCQsFBR Mathematics15 MCQsJEST Mathematics15 MCQsJunior Clerk Test Mathematics15 MCQsLAT Mathematics15 MCQsNADRA Mathematics15 MCQsPST Mathematics15 MCQsSub Registrar Test Mathematics15 MCQsAJKPSC Mathematics10 MCQsAssistant BS-16 Test Mathematics10 MCQsBPSC Mathematics10 MCQsECP Mathematics10 MCQsFIA Mathematics10 MCQsFPSC Mathematics10 MCQsGBPSC Mathematics10 MCQsIB Mathematics10 MCQsIntelligence Officer Mathematics10 MCQsKPPSC Mathematics10 MCQsMES Mathematics10 MCQsNAB Mathematics10 MCQsNational Highways and Motorway Police Test Mathematics10 MCQsPakistan Railways Recruitment Test Mathematics10 MCQsPCS Mathematics10 MCQsPIA Mathematics10 MCQsPPSC Mathematics10 MCQsPunjab Police ASI Test Mathematics10 MCQsPunjab Police Sub Inspector Test Mathematics10 MCQsSNGPL Mathematics10 MCQsSPSC Mathematics10 MCQsSub Engineer Civil Test Mathematics10 MCQsSub Engineer Electrical Test Mathematics10 MCQsSub Engineer Mechanical Test Mathematics10 MCQsTehsildar and Naib Tehsildar Test Mathematics10 MCQsWAPDA Mathematics10 MCQsANF Mathematics5 MCQsASF Mathematics5 MCQsCTD Mathematics5 MCQsElite Police Force Test Mathematics5 MCQsPakistan Army Soldier Test Mathematics5 MCQsPakistan Rangers Test Mathematics5 MCQsPERA Force Test Mathematics5 MCQsPunjab Police Constable Test Mathematics5 MCQsRescue 1122 Test Mathematics5 MCQs

More Averages questions

The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is___________?

The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg. Find the average weights of all the boys in the class.

If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is__________?

The mean marks of 30 students in a class is 58.5. Later on it was found that 75 was wrongly recorded as 57. Find the correct them.

The average of women and child workers in a factory was 15%yr. The average age of all the 16 children was 8yr and average age of women workers was 22 yrs if ten women workers were married then the number of unmarried women workers were________?

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ration of the number of boys to the number of girls in the class is___________?