
Sir,
could you please help in following problem also:
Two motorists Anil and Sunil are practicing with two different sports car on a circular tract. Both start from the same point on the circular track. Anil completes 1 round in 1 min and Sunil takes 2 min to complete a round. While Anil maintains the same speed for all rounds, Sunil halves his speed after the completion of each round. How many times Anil and Sunil will meet between the 6th and 9th round of Sunil (6th and 9th excluded)? Assume the speed of Sunil remains constant throughout each round and changes after completion of that round.
a) 260 b) 347 c) 382 d) None of these
Solution: Sir, I calculated as follows and got 382 as answer. However, the ans is d. Please tell me what did I do wrong.
Let Anil speed = a Then Sunil speed will be a/2
In 7th round Sunil speed will be a/2^{7} and in 8th round the speed will be a/2^{8}. So, the no. of times Sunil meets Anil in 7th round is 127 and in 8th round, it is 255.
Total no. of times = 127+255=382.
