thesocialnetwork wrote:

At a games stall, an electronic device displays a three-digit number from 000 to 999. When a button is pressed, each number has an equal chance of being displayed. Find the probabilityh that the three digits displayed

i) Have a sum of at least 24,

ii) are identical, given that the sum of the three numbers is at least 24.

i) P(sum of at least 24) = Number of Favorable Cases / Number of Possible Cases

**Favorable cases:** 999; 998; 997; 996; 988; 987; 888

If you do the permutation you will get

**20 cases**, then:

P(sum of at least 24) = Number of Favorable Cases / Number of Possible Cases

ii)

**Favorable cases:** **999**;

**888** just 2, as the possible cases are 20 then the result will be