Question

a building security code has two numeric digits 0 through 9 followed by two letters what is the probability that the first digit is 9 and the last letter is a

Answer 1

`\begin{gathered} \text{First step, calculate all securities code} \\ Number,_{}Number,letter,_{}letter_{} \\ \text{there are 10 numbers from 0 to 9} \\ \text{there are 26 letters from a to z} \\ 10\cdot10\cdot26\cdot26=\text{ 67600} \\ There\text{ are 67,600 securities code} \\ Second\text{ step, calculate all securities code with the condition},\text{ P(A)} \\ 9,\text{ }Number,letter,_{}a \\ \text{there are 10 numbers from 0 to 9} \\ \text{there are 26 letters from a to z} \\ 10\cdot26=260 \\ There\text{ are 260 securities code with the condition} \\ P(A)=\frac{260}{\text{67,600}} \\ P(A)=0.003846 \\ P(A)=0.3846\text{ percent} \\ The\text{ probability is }0.3846\text{\%} \\ \end{gathered}`