जॉइन Examsbookउत्तर : 1. "88572"
A secret can be told to only 3 persons in 3 minutes. Each person in turn tells 3 other persons in the next 3 minutes and the processes continues accordingly. In 30 minutes how many persons can be told this secret in this way ?5
प्र: A secret can be told to only 3 persons in 3 minutes. Each person in turn tells 3 other persons in the next 3 minutes and the processes continues accordingly. In 30 minutes how many persons can be told this secret in this way ?
- 188572true
- 277854false
- 399584false
- 455654false
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उत्तर : 1. "88572"
व्याख्या :
Answer: A) 88572 Explanation: Given a secret is told to 3 persons in 3 minutes.And if the process continues with each person saying 3 other persons,In 30 minutes => the rocess for 10 times because each person time is 3 minutes.Required number of persons = 3 + 32 + 33 + .... + 39 + 310 Now it forms a geometric progression, Sum to n terms is S = arn - 1r - 1 Here a = 3, r = 3 => 59048 x 3 /2 = 88572.