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Phrases Statistics Measures Of Central Tendency PYQ



The mean of 5 observation is 5 and their variance is 12.4. If three of the observations are 1,2 and 6; then the mean deviation from the mean of the data is:





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If the mean deviation 1, 1+d, 1+2d, … , 1+100d from their mean is 255, then d is equal to






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If  and , then a possible value of n is among the following is 





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Not Available






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The 10th and 50th percentiles of the observation 32, 49, 23, 29, 118 respectively are





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The first three moments of a distribution about 2 are 1, 16, -40 respectively. The mean and variance of the distribution are





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If a1,a2,,an are any real numbers and n is any positive integer, then





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In a reality show, two judges independently provided marks base do the performance of the participants. If the marks provided by the second judge are given by Y = 10.5 + 2x, where X is the marks provided by the first judge. If the variance of the marks provided by the second judge is 100, then the variance of the marks provided by the first judge is:





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The mean of 25 observations was found to be 38. It was later discovered that 23 and 38 were misread as 25 and 36, then the mean is





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Given a set A with median m1=2 and set B with median m2=4
What can we say about the median of the combined set?





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Given two sets:

  • Set A has median m1=2
  • Set B has median m2=4

What can we say about the median of the combined set AB?

✅ Answer:

The combined median depends on the size and values of both sets.

Without that information, we only know that:

Combined Median[2,4]

So, the exact median cannot be determined with the given data.



It is given that the mean, median and mode of a data set is 1,3x and 9x respectively. The possible values of the mode is





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Solution

Mean, Median, and Mode Relation

Given:

  • Mean = 1
  • Median = 3x
  • Mode = 9x

Use empirical formula:

Mode=3Median2Mean

9x=33x2(3x)2=33x2

Let y=3x, then:

y2=3y2y23y+2=0(y1)(y2)=0

So, y=1 or 29x=y2=1 or 4

✅ Final Answer: 1 or 4



If the mean of the squares of first n natural numbers be 11, then n is equal to?





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The standard deviation of 20 numbers is 30. If each of the numbers is increased by 4, then the new standard deviation will be  





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If a variable takes values 0, 1, 2,…, 50 with frequencies 1,50C1,50C2,..,50C50, then the AM is





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In a group of 200 students, the mean and the standard deviation of scores were found to be 40 and 15, respectively. Later on it was found that the two scores 43 and 35 were misread as 34 and 53, respectively. The corrected mean of scores is:





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The mean deviation from the mean of the AP a, a + d, a + 2d, ..., a + 2nd, is:





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Consider the following frequency distribution table.
 Class Interval 10-20 20-30 30-40 40-5050-60  60-7070-80 
 Frequency 180f1 34 180 136 f250 
If the total frequency is 686 and the median is 42.6, then the value of f1;and f2 are 





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If the mean deviation of the numbers 1, 1 + d, 1 + 2d, ....., 1 + 100d from their mean is 255, then the value of d is





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A, B, C are three sets of values of x: 
A: 2,3,7,1,3,2,3 
B: 7,5,9,12,5,3,8 
C: 4,4,11,7,2,3,4 
Select the correct statement among the following:





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Solution

A: 2, 3, 7, 1, 3, 2, 3 
Increasing Order : A: 1, 2, 2, 3, 3, 3, 7 
Mode = 3 (occurs maximum number of times) 
Median = 3 (the middle term) 

Mean =(1+2+2+3+3+3+7)7
=217=3

Hence. Mean=Median=Mode


Standard deviation for the following distribution is 
 Size of item10 11 12 
 Frequency 313  8










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Total number of items in the distribution = Σ fi = 3 + 6 + 9 + 13 + 8 + 5 + 4 = 48.

The Mean (x̅) of the given set = fixifi.

⇒ x̅ = 6×3+7×6+8×9+9×13+10×8+11×5+12×448=43248 = 9.

Let's calculate the variance using the formula: σ2=x2inˉx2.

xi2n=62×3+72×6+82×9+92×13+102×8+112×5+122×448=401248 = 83.58.

∴ σ2 = 83.58 - 92 = 83.58 - 81 = 2.58.

And, Standard Deviation (σ) = σ2=Variance=2.58 ≈ 1.607.



The mean of 5 observation is 5 and their variance is 124. If three of the observations are 1,2 and 6; then the mean deviation from the mean of the data is:






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For a group of 100 candidates, the mean and standard deviation of scores were found to be 40 and 15 respectively. Later on, it was found that the scores 25 and 35 were misread as 52 and 53 respectively. Then the corrected mean and standard deviation corresponding to the corrected figures are





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Solution

Corrected Mean and Standard Deviation

Original Mean: 40, Standard Deviation: 15

Two scores were misread: 25 → 52 and 35 → 53

Corrected Mean:

μ=3955100=39.55

Corrected Standard Deviation:

σ=178837100(39.55)214.96

✅ Final Answer: Mean = 39.55, Standard Deviation ≈ 14.96



Consider the following frequency distribution table.
 Class interval 10-20 20-3030-40 40-50  50-60 60-7070-80 
 Frequency 180 f1 34180  136 f250 






If the total frequency is 685 & median is 42.6 then the values of f1  and f2  are





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Solution

Median & Frequency Table

Given: Median = 42.6, Total Frequency = 685

Using Median Formula:

Median=L+(N/2Ff)h

  • Median Class: 40–50
  • Lower boundary L=40
  • Frequency f=180
  • Class width h=10
  • Cumulative freq before median class F=214+f1

Substituting values:

42.6=40+(128.5f1180)10f1=82

Using total frequency:

662+f2=685f2=23

✅ Final Answer: f1=82,f2=23



The average marks of boys in a class is 52 and that of girls is 42. The average marks of boys and girls combined is 50. The percentage of boys in the class is





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