Question

6. Explain why 7x11×13+13 and 7×6×5×4×3×2×1+5 are composite numbers.
7. There is a circular path around a sports field. Sonia takes 18 minutes to drive one round
of the field, while Ravi takes 12 minutes for the same. Suppose they both start at the
same point and at the same time, and go in the same direction. After how many minutes
will they meet again at the starting point?
Revisiting Irrational Numbers​

Answer 1

Answer:

Step-by-step explanation:

6. 7x11x13+13

13(7x11x1+1)

13(78)

78 can be expressed as a product of prime numbers

Therefore it is composite

Similarly

7x6x5x4x3x2x1+5

5(7x6x1x4x3x2x1+1)

5(1009)

1009 can be expressed as a product of prime numbers

It is composite

7. Time taken by Saina to complete one round = 18mins

Time taken by Ravi to complete one round = 12 mins

By taking LCM of the time taken by both of them we get 36

Thus they will meet after 36mins

Hope you understand