The mean marks of 100 students were calculated as 65. At the time of checking it was found the marks 40 and 50 was wrongly copied and weeded out Find the correct mean marks.​

[ Because those two numbers are removed you need to reduce the number of terms to 98. ]

☆Solution☆

N=100

Mean=65

(Wrong Numbers=40,50)

Now,

Mean=Sum/No. of items

or,65=Sum/100

▪Sum=65×100=6500

After removing the unnecessary numbers,

New Sum=6500-40-50=6410

New no.of terms(N)=100-2=98

Now,

New Mean=New Sum/New N

=6410/98

=65.41

Ans.

Step-by-step explanation:

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.