In the front of your exercise book... Underline the last piece of work Write today’s date (Friday, 14 September 2018) How Gossip Spreads Imagine you know a secret and you share it with two of your best friends during the first lesson of the day Of course you remind them not to tell anyone but during period two your best friends just cannot resist passing on your gossip to two of their best friends If this process happens every lesson (five lessons in a day) how many people will know your secret by the end of the day?

Solution... Period 1: Yourself + 2 people know the secret (1 + 2 = 3) 2 people each tell 2 people (adding 4 people) (1 + 2 + 4 = 7) Period 3: 4 people each tell 2 people (adding 8 people) (1 + 2 + 4 + 8 = 15)

Solution... Period 4: 8 people each tell 2 people (adding 16 people) (1 + 2 + 4 + 8 + 16 = 31) Period 5: 16 people each tell 2 people (adding 32 people) (1 + 2 + 4 + 8 + 16 +32 = 63) Not much of a secret anymore!!!! In general, after n periods, how many people will know your secret?