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Mathematics

Assertion (A) : The first quartile of the observations 15, 14, 21, 11, 19, 10, 18 is 10.

Reason (R) : For an ungrouped data, containing n observations, lower quartile is given by

Q1 = n - 14\dfrac{\text{n - 1}}{4} th observation, if n is odd.

  1. A is true, R is false

  2. A is false, R is true

  3. Both A and R are true

  4. Both A and R are false

Measures of Central Tendency

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Answer

Observations arranging in ascending order = 10, 11, 14, 15, 18, 19, 21

Here, n = 7

We know that,

If the variates are arranged in ascending order, then the observation lying midway between the lower extreme and the median is called the Lower quartile or First quartile.

Q1 = n + 14\dfrac{\text{n + 1}}{4} th observation, if n is odd.

= 7+14=84\dfrac{7 + 1}{4} = \dfrac{8}{4} = 2.

∴ Assertion (A) is false.

For an ungrouped data, containing n observations, lower quartile is given by

Q1 = n + 14\dfrac{\text{n + 1}}{4} th observation, if n is odd.

∴ Reason (R) is false.

Hence, Option 4 is the correct option.

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