Question

4 Connie is trying to guess her brother's new mobile phone number. Her brother has told Connie the following information about the number: It is an 11-digit number. It starts with the digits 07. All of the remaining digits are odd. If Connie uses this information to randomly guess her brother's number, what is the probability that she will guess the correct phone number on the first try? Give your answer in standard form to 3 s.f.​

Answer 1

Explanation:

07 x x x x x x x x x

Nine x's can be any odd number ( 1 3 5 7 9 = five choices)

5^9 = 1 953 125 choices

she has a one in 1 953 125 chance of getting it correct

1/ 1953 125 chance = 5.12 x 10^-7 chance