A security alarm requires a four-digit code. The code can use the digits 0 - 9 and the digits cannot be repeated. Which expression can be used to determine the probability of the alarm code beginning with a number greater than 7 ?
Answer
A
the fraction with numerator open paren sub 10 cap c sub 1 close paren times open paren sub 9 cap c sub 3 close paren and denominator sub 10 cap c sub 4
B
the fraction with numerator open paren sub 2 cap c sub 1 close paren times open paren sub 9 cap c sub 3 close paren and denominator sub 10 cap c sub 4
C
the fraction with numerator open paren sub 10 cap p sub 1 close paren times open paren sub 9 cap p sub 3 close paren and denominator sub 10 cap p sub 4
D
the fraction with numerator open paren sub 2 cap p sub 1 close paren times open paren sub 9 cap p sub 3 close paren and denominator sub 10 cap p sub 4