Two friends share a secret on the first day. The second date they each till one another different friend, so now for people know the secret.

Question

Two friends share a secret on the first day. The second date they each till one another different friend, so now for people know the secret. On day three or four till a different person, now ate know the secret. The secret keeps growing in this week. On what day will the number who know the secret past 1 million

in progress 0
Isabella 3 days 2021-10-11T12:50:56+00:00 1 Answer 0

Answers ( )

    0
    2021-10-11T12:52:43+00:00

    Answer:

    The 20th day

    Step-by-step explanation:

    On the first day, number of people who know the secret=2

    Number of people On the second day =2X2=4

    Number of people On the third day =4X2=8

    We can see that on each passing day, the number keeps doubling.

    This is an example of a geometric progression.

    Now we are to determine the number of days when the number of people who know the secret will grow past 1,000,000

    For the G.P. 2,4,8,…

    a=2, common ratio, r= 2

    Uₙ=arⁿ⁻¹

    arⁿ⁻¹>1000000

    2X2ⁿ⁻¹>1000000

    2ⁿ⁻¹⁺¹>1000000

    2ⁿ>1000000<2²⁰=1048576

    2ⁿ<2²⁰

    n<20

    It means on the 20th day, more than 1 million people will have been told the secret

Leave an answer

45:7+7-4:2-5:5*4+35:2 =? ( )