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CPT Section D Quantitative Aptitude Chapter 15 
Prof. Bharat Koshti 
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CPT Section D Quantitative Aptitude Chapter 15 
Prof. Bharat Koshti 
Theory of estimation : 
It deals with estimating unknown values of the Population 
parameters. 
There are two types of estimation techniques : 
1.Point Estimation 
2. Interval Estimation 
1. Point Estimation: When a single value is proposed to 
estimate, it is called as Point estimation. 
Page 3


CPT Section D Quantitative Aptitude Chapter 15 
Prof. Bharat Koshti 
Theory of estimation : 
It deals with estimating unknown values of the Population 
parameters. 
There are two types of estimation techniques : 
1.Point Estimation 
2. Interval Estimation 
1. Point Estimation: When a single value is proposed to 
estimate, it is called as Point estimation. 
1. Suppose the unknown parameter is ?. 
(e.g. ? = Population Mean) 
2. We take a sample of size ‘n’ from the population of      
size ‘N’ at random. So we get sample observations  
( x
1
, x
2
, x
3
,  ……………… x
n
  )  
3. Now based on these sample observations we  
  construct statistic T (e.g. Sample Mean) which will estimate ? 
Page 4


CPT Section D Quantitative Aptitude Chapter 15 
Prof. Bharat Koshti 
Theory of estimation : 
It deals with estimating unknown values of the Population 
parameters. 
There are two types of estimation techniques : 
1.Point Estimation 
2. Interval Estimation 
1. Point Estimation: When a single value is proposed to 
estimate, it is called as Point estimation. 
1. Suppose the unknown parameter is ?. 
(e.g. ? = Population Mean) 
2. We take a sample of size ‘n’ from the population of      
size ‘N’ at random. So we get sample observations  
( x
1
, x
2
, x
3
,  ……………… x
n
  )  
3. Now based on these sample observations we  
  construct statistic T (e.g. Sample Mean) which will estimate ? 
T is a single value obtained from the sample & 
is known as point estimator. 
The point estimator of Population Mean(µ), 
Population Standard Deviation(s) & Population 
Proportion(P) are the corresponding sample 
Mean(x¯),Sample Standard Deviation(s) & 
Sample Proportion(p).   
Page 5


CPT Section D Quantitative Aptitude Chapter 15 
Prof. Bharat Koshti 
Theory of estimation : 
It deals with estimating unknown values of the Population 
parameters. 
There are two types of estimation techniques : 
1.Point Estimation 
2. Interval Estimation 
1. Point Estimation: When a single value is proposed to 
estimate, it is called as Point estimation. 
1. Suppose the unknown parameter is ?. 
(e.g. ? = Population Mean) 
2. We take a sample of size ‘n’ from the population of      
size ‘N’ at random. So we get sample observations  
( x
1
, x
2
, x
3
,  ……………… x
n
  )  
3. Now based on these sample observations we  
  construct statistic T (e.g. Sample Mean) which will estimate ? 
T is a single value obtained from the sample & 
is known as point estimator. 
The point estimator of Population Mean(µ), 
Population Standard Deviation(s) & Population 
Proportion(P) are the corresponding sample 
Mean(x¯),Sample Standard Deviation(s) & 
Sample Proportion(p).   
Ex1. Consider sample observations 
14,15,6,17,28  from population of 100 units. Find 
an estimate of population mean.    
Estimate of µ is given by X¯  
X¯ = (14+15+6+17+28)/5 
X¯ = 16 
Hence, estimate of µ is 16.