Lakshya Education MCQs

Question: For which data set, the mean is not a good representative measures of central tendency.
Options:
A.There are 7 classes with the below frequencies. {10, 12, 15, 17, 14, 15, 17}
B.There are 6 classes with the below frequencies. {2, 20, 25, 17, 19, 22}
C.There are 7 classes with the below frequencies. {5, 7, 5, 6, 4, 5, 7}
D.There are 6 classes with the below frequencies. {17, 20, 25, 17, 19, 22}
Answer: Option B
: B

We know that extreme values in the data affect the mean. Here only for the data set{2, 20, 25, 17, 19, 22}, we find the extreme value as one class has the frequency as 2 and the others have frequency 20, 25, 17, 19 and 22.

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More Questions on This Topic :

Question 1. The times (in seconds) taken by 150 athelets to run a 110 m hurdle race are tabulated below

Class13.8141414.214.214.414.414.614.614.814.815Frequency245714820

The number  of atheletes who completed the race in less than 14.6 s is
  1.    11
  2.    71
  3.    82
  4.    130
Answer: Option C
: C

The number of atheletes who completed the race in less than 14.6 = 2 + 4 + 5 + 71 = 82
Question 2. The median for grouped data is formed by using the formula:
  1.    l+(n2−cff ) ×h
  2.    l−(n2−cff ) ×h.
  3.    l+(n2+cff ) ×h.
  4.    l+2n
Answer: Option A
: A

The median for grouped data is formed by l+(n2cff ) ×h. Where l is lower class limit of median class.
n is total number of observations.
cf is the cumulative frequency of the class preceding the median class.
f is the frequency of the median class and h is the class size.
Question 3. In the assumed mean method, if A is the assumed mean, then deviation di is : 
  1.    xi−A
  2.    xi+A
  3.    xi
  4.    A−xi
Answer: Option A
: A

The deviation is di=xiA
Question 4.
  1.     1 - 2
  2.    2 - 3
  3.     6 - 7 
  4.     7 - 8
Answer: Option B
: B

Here we locate a class with the maximum frequency. From the given table we find the maximum frequency as 12 whose class is 2 - 3. Therefore the modal class is 2 - 3.
Question 5. The following data shows monthly savings of 100 families . Calculate the mode of the given frequency distribution.

        Monthly savings(Rs)                Number of families        10002000142000300015300040002140005000275000600025
  1.    4790
  2.    4760
  3.    4750
  4.    4780
Answer: Option C
: C

Modal class is 4000-5000 within f1 = 27, f0 = 21, f2 = 25, I = 4000, h = 1000 Mode = l +f1f02f1f0f2×h Mode = 4000 + 68×1000 = 4750
Question 6. The following table gives the life time of 200 neon lamps. Find the median class.

  1.    2500 - 3000
  2.    1000 - 1500
  3.    1500 - 2000
  4.    3000 - 3500
Answer: Option A
: A


The median class is identified as the class whose cumulative frequency will be greater than n2, where 'n' is the sum of the frequencies. (n=200).
Next, we divide 200 by 2.

n2=2002=100

We now locate the class whose cumulative frequency is greater than 100.
"2500 - 3000" is the class whose cumulative frequency 155 is greater than 100.
The median class is 2500 - 3000.

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