math games grade 8

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Question: For the post of 5 teachers, there are 23 applicants. 2 posts are reserved for S.C. candidates and there are 7 S.C. candidates among applicants. In how many ways can the selection be made? Answer: There are 23 applicants. Among this, 7 are S.C. candidates. We have to select 2 S..

There are 8 ways of travelling from A to B and seven ways for the return journey, since he cannot come by the same car. Hence, the number of ways of making both the journeys is 8 x 7 = 5..

Question: How many six digits telephone numbers can be made if each number starts with 45 and no digit appears more than once? Answer: The first two places are reserved for 4 and 5. The remaining 8 digits can be arranged in P(8,4) = 8.7.6.5 = 1680 way..

Number of ways of filling hundred's place = 2 Number of ways of filling ten's place = 2 Number of ways of filling unit's place = 2 By the fundamental principle of counting, the total number of numbers = 2 x 2 x 2 = 8..

Question: A lady wants to select one cotton saree and one polyster saree from a collection of 8 cotton sarees and 11 polyster sarees. In how many ways can the lady choose the two sarees? Answer: Here, there are two events E 1 and E 2 . E 1 = Selection of one cotton saree fro..

Question: Convert the following into factorials: i) 5.6.7.8.9.10 ii) 4.6.8.10.12 Answer: i) ii) ..

1. 2 and 3 are two digits and with these digits, the numbers 32 and 23 are formed. Although both numbers viz., 32 and 23 consist of the digits 2 and 3, the order of digits is different. Each of the above arrangements is called a 'permutation'. Thus, the number of arrangements or permutations of tw..

8! = 8 x 7 x 6 x 5 x4 x 3 x 2 x 1 = 40320 ..

Using determinants, find the area of triangle whose vertices are (2, -7), (1, 3), (10, 8). Solution: (x 1 , y 1 ) = (2, -7) (x 2 , y 2 ) = (1, 3) (x 3 , y 3 ) = (10, 8) Area of the triangle = -47.5 Since area has to be a positive quantity, it is given by 47.5 sq.units..