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Statistics question

2023 · Shift 1 · Q32
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Statistics question

2023 · Shift 1 · Q32

JEE AdvancedMathematicsStatisticsMCQ+3 / −1
Consider the given data with frequency distribution

xi38111054fi523244\begin{array}{ccccccc} x_i & 3 & 8 & 11 & 10 & 5 & 4 \\ f_i & 5 & 2 & 3 & 2 & 4 & 4 \end{array}xi​fi​​35​82​113​102​54​44​

Match each entry in List-I to the correct entries in List-II.

List - I List - II
(P) The mean of the above data is (1) 2.5
(Q) The median of the above data is (2) 5
(R) The mean deviation about the mean of the above data is (3) 6
(S) The mean deviation about the median of the above data is (4) 2.7
(5) 2.4

The correct option is:
  1. A
    (P)→(3)  (Q)→(2)  (R)→(4)  (S)→(5)(P) \rightarrow(3) ~~ (Q) \rightarrow(2) ~~ (R) \rightarrow(4) ~~ (S) \rightarrow(5)(P)→(3)  (Q)→(2)  (R)→(4)  (S)→(5)
  2. B
    (P)→(3)  (Q)→(2)  (R)→(1)  (S)→(5)(P) \rightarrow(3) ~~ (Q) \rightarrow(2) ~~ (R) \rightarrow(1) ~~ (S) \rightarrow(5)(P)→(3)  (Q)→(2)  (R)→(1)  (S)→(5)
  3. C
    (P)→(2)  (Q)→(3)  (R)→(4)  (S)→(1)(P) \rightarrow(2) ~~ (Q) \rightarrow(3) ~~ (R) \rightarrow(4) ~~ (S) \rightarrow(1)(P)→(2)  (Q)→(3)  (R)→(4)  (S)→(1)
  4. D
    (P)→(3)  (Q)→(3)  (R)→(5)  (S)→(5)(P) \rightarrow(3) ~~ (Q) \rightarrow(3) ~~ (R) \rightarrow(5) ~~ (S) \rightarrow(5)(P)→(3)  (Q)→(3)  (R)→(5)  (S)→(5)
View written solutionFree

Correct answer: A

Step 1: Organize the data and calculate basic sums

The given data with frequency distribution is: xi38111054fi523244\begin{array}{ccccccc} x_i & 3 & 8 & 11 & 10 & 5 & 4 \\ f_i & 5 & 2 & 3 & 2 & 4 & 4 \end{array}xi​fi​​35​82​113​102​54​44​ First, let's arrange the data in ascending order of xix_ixi​ to make calculations for the median and other measures easier.

xix_ixi​fif_ifi​ (Frequency)
35
44
54
82
102
113

Now, let's calculate the total number of observations, N=∑fiN = \sum f_iN=∑fi​. N=5+4+4+2+2+3=20N = 5 + 4 + 4 + 2 + 2 + 3 = 20N=5+4+4+2+2+3=20.

Step 2: Calculate the Mean (P)

The formula for the mean (xˉ\bar{x}xˉ) of a frequency distribution is xˉ=∑fixi∑fi\bar{x} = \frac{\sum f_i x_i}{\sum f_i}xˉ=∑fi​∑fi​xi​​. Let's calculate ∑fixi\sum f_i x_i∑fi​xi​:

xix_ixi​fif_ifi​fixif_i x_ifi​xi​
3515
4416
5420
8216
10220
11333
Total20120

∑fixi=120\sum f_i x_i = 120∑fi​xi​=120.

Mean, xˉ=12020=6\bar{x} = \frac{120}{20} = 6xˉ=20120​=6.

So, (P) The mean of the above data is 6, which corresponds to (3) in List-II.

Step 3: Calculate the Median (Q)

To find the median, we need the cumulative frequency (c.f.). The total number of observations is N=20N=20N=20 (even). The median is the average of the N2th\frac{N}{2}^{th}2N​th and (N2+1)th(\frac{N}{2} + 1)^{th}(2N​+1)th observations, i.e., the 10th and 11th observations.

Let's create the cumulative frequency table:

xix_ixi​fif_ifi​c.f.
355
449
5413
8215
10217
11320

The cumulative frequency just greater than or equal to 10 is 13, which corresponds to xi=5x_i = 5xi​=5. This means the 10th observation is 5. Since the 10th, 11th, 12th, and 13th observations are all 5, the 11th observation is also 5.

Median, M=10th observation+11th observation2=5+52=5M = \frac{10^{th} \text{ observation} + 11^{th} \text{ observation}}{2} = \frac{5 + 5}{2} = 5M=210th observation+11th observation​=25+5​=5.

So, (Q) The median of the above data is 5, which corresponds to (2) in List-II.

Step 4: Calculate the Mean Deviation about the Mean (R)

The formula for the mean deviation about the mean is MD(xˉ)=∑fi∣xi−xˉ∣NMD(\bar{x}) = \frac{\sum f_i |x_i - \bar{x}|}{N}MD(xˉ)=N∑fi​∣xi​−xˉ∣​. We have xˉ=6\bar{x} = 6xˉ=6 and N=20N = 20N=20.

Let's calculate ∑fi∣xi−6∣\sum f_i |x_i - 6|∑fi​∣xi​−6∣:

| xix_ixi​ | fif_ifi​ | ∣xi−xˉ∣=∣xi−6∣|x_i - \bar{x}| = |x_i - 6|∣xi​−xˉ∣=∣xi​−6∣ | fi∣xi−xˉ∣f_i |x_i - \bar{x}|fi​∣xi​−xˉ∣ | | :---: | :---: | :--------------------------: | :-----------------------: | | 3 | 5 | 3 | 5×3=155 \times 3 = 155×3=15 | | 4 | 4 | 2 | 4×2=84 \times 2 = 84×2=8 | | 5 | 4 | 1 | 4×1=44 \times 1 = 44×1=4 | | 8 | 2 | 2 | 2×2=42 \times 2 = 42×2=4 | | 10 | 2 | 4 | 2×4=82 \times 4 = 82×4=8 | | 11 | 3 | 5 | 3×5=153 \times 5 = 153×5=15 | | Total | 20 | | 54 |

MD(xˉ)=5420=2.7MD(\bar{x}) = \frac{54}{20} = 2.7MD(xˉ)=2054​=2.7.

So, (R) The mean deviation about the mean is 2.7, which corresponds to (4) in List-II.

Step 5: Calculate the Mean Deviation about the Median (S)

The formula for the mean deviation about the median is MD(M)=∑fi∣xi−M∣NMD(M) = \frac{\sum f_i |x_i - M|}{N}MD(M)=N∑fi​∣xi​−M∣​. We have M=5M = 5M=5 and N=20N = 20N=20.

Let's calculate ∑fi∣xi−5∣\sum f_i |x_i - 5|∑fi​∣xi​−5∣:

| xix_ixi​ | fif_ifi​ | ∣xi−M∣=∣xi−5∣|x_i - M| = |x_i - 5|∣xi​−M∣=∣xi​−5∣ | fi∣xi−M∣f_i |x_i - M|fi​∣xi​−M∣ | | :---: | :---: | :-----------------------: | :-------------------: | | 3 | 5 | 2 | 5×2=105 \times 2 = 105×2=10 | | 4 | 4 | 1 | 4×1=44 \times 1 = 44×1=4 | | 5 | 4 | 0 | 4×0=04 \times 0 = 04×0=0 | | 8 | 2 | 3 | 2×3=62 \times 3 = 62×3=6 | | 10 | 2 | 5 | 2×5=102 \times 5 = 102×5=10 | | 11 | 3 | 6 | 3×6=183 \times 6 = 183×6=18 | | Total | 20 | | 48 |

MD(M)=4820=125=2.4MD(M) = \frac{48}{20} = \frac{12}{5} = 2.4MD(M)=2048​=512​=2.4.

So, (S) The mean deviation about the median is 2.4, which corresponds to (5) in List-II.

Step 6: Match the entries and select the correct option

Based on our calculations:

  • (P) Mean is 6 →\rightarrow→ (3)
  • (Q) Median is 5 →\rightarrow→ (2)
  • (R) Mean deviation about mean is 2.7 →\rightarrow→ (4)
  • (S) Mean deviation about median is 2.4 →\rightarrow→ (5)

The correct matching is (P)→(3)  (Q)→(2)  (R)→(4)  (S)→(5)(P) \rightarrow(3) ~~ (Q) \rightarrow(2) ~~ (R) \rightarrow(4) ~~ (S) \rightarrow(5)(P)→(3)  (Q)→(2)  (R)→(4)  (S)→(5).

This corresponds to option A.

Previous

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