Question:

The maximum number of points of intersection of 8 circles of unequal radii is 56. The maximum number of points into which 4 circles of unequal radii and 4 non coincident straight lines intersect, is 50.

Updated On: Sep 30, 2023
  • Statement-1 is true, Statement-2 is true, Statement-2 is a correct explanation for Statement -1
  • Statement -1 is true, Statement -2 is true ; Statement-2 is NOT a correct explanation for Statement - 1
  • Statement -1 is false, Statement -2 is true
  • Statement - 1 is true, Statement- 2 is false
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The Correct Option is B

Solution and Explanation

Two circles intersect in 2 points. $\therefore$ Maximum number of points of intersection $= 2 ?$ number of selections of two circles from 8 circles $= 2 ? ^8C_2 = 2 ? 28 = 56$ Statement $2 : 4$ lines intersect each other in $^4C_2 = 6$ points 4 circles intersect each other in $2 ? ^4C_2 = 12$ points. Further, one lines and one circle intersect in two points. So 4 lines will intersect four circles in 32 points. Maximum number of points $= 6 + 12 + 32 = 50$
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Concepts Used:

Combinations

The method of forming subsets by selecting data from a larger set in a way that the selection order does not matter is called the combination.

  • It means the combination of about ‘n’ things taken ‘k’ at a time without any repetition.
  • The combination is used for a group of data where the order of data does not matter.
  • For example, Imagine you go to a restaurant and order some soup.
  • Five toppings can complement the soup, namely:
    • croutons,
    • orange zest,
    • grated cheese,
    • chopped herbs,
    • fried noodles.

But you are only allowed to pick three.

  • There can be several ways in which you can enhance your soup with savory.
  • The selection of three toppings (subset) from the five toppings (larger set) is called a combination.

Use of Combinations:

It is used for a group of data (where the order of data doesn’t matter).