Question

10. The coefficient of rank correlation between marks in Quantitative Mathematics and Economics
obtained by a certain group of students is 7/11. The sum of the squares of differences in ranks is 60.
What is the number of students in the group?​

Answer 1

The question is:

if the rank correlation coefficient between marks in management and maths for a group of students is 7/11 or 0.6 and the sum of squares of the differences in ranks is 66, what is the number of students in the group​?

The number of students is 10

Step-by-step explanation:

Given that,

Rank Correlation coefficient(P) = 7/11 or 0.6

The sum of the squares of differences(∑d^2) = 66

Let n be the number of students

As we know,

Rank Correlation coefficient(P) = (1 - 6) ∑d^2/n(n^2 - 1)

By putting the given values in the formula, we get

⇒ 0.6 = 1 - (6 * 66)/n(n^2 - 1)

⇒ 1 - 0.6 = 396/n(n^2 - 1)

⇒ 0.4 = 396/n(n^2 - 1)

⇒ n(n^2 - 1) = 396/0.4

⇒ n(n^2 - 1) = 990

∵ 10(10^2 - 1) = n(n^2 - 1)

n = 10

Thus, the number of students is 10.

Learn more: Find the number of students

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